Backport #27231 #27259 manually

---------

Co-authored-by: delvh <dev.lh@web.de>

Introduce `AvatarUtils`, no need to pass `$.Context` to every
sub-template, and simplify the template helper functions.

The correct thing to do is to translate the entire phrase into a single
string. The previous translation assumed all languages have a space
between the "joined on" and the date (and that "joined on" comes before
the date).

Some languages, like Hebrew, have no space between the "joined on" and
the date. For example:
```ini
joined_on=נרשם ב-%s
```
("joined" becomes נרשם, "on" is ב and when paired with a date we use a
dash to connect ב with the date)

Fixes #24418

Before, 500 error


![image](https://user-images.githubusercontent.com/2114189/234170176-403ffd1b-ec27-42be-bff9-86184dc8d74d.png)

This refactors the `shared/datetime/short|long|full` templates into a
template helper function, which allows us to render absolute date times
within translatable phrases.

- Follows #23988
- The first attempt was in #24055
- This should help #22664 

Changes:
1. Added the `DateTime` template helper that replaces the
`shared/datetime/short|long|full` templates
2. Used find-and-replace with varying regexes to replace the templates
from step 1 (for example, `\{\{template "shared/datetime/(\S+) \(dict
"Datetime" ([^"]+) "Fallback" ([^\)]+\)?) ?\)?\}\}` -> `{{DateTime "$1
$2 $3}}`)
3. Used the new `DateTime` helper in the issue due date timestamp
rendering

# Before

![image](https://user-images.githubusercontent.com/20454870/233791256-b454c455-aca0-4b76-b300-7866c7bd529e.png)

# After

![image](https://user-images.githubusercontent.com/20454870/233790809-c4913355-2822-4657-bb29-2298deb6d4b3.png)

---------

Signed-off-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

- Added [GitHub's `relative-time` element](https://github.com/github/relative-time-element)
- Converted all formatted timestamps to use this element
- No more flashes of unstyled content around time elements
- These elements are localized using the `lang` property of the HTML file
- Relative (e.g. the activities in the dashboard) and duration (e.g.
server uptime in the admin page) time elements are auto-updated to keep
up with the current time without refreshing the page
- Code that is not needed anymore such as `formatting.js` and parts of `since.go` have been deleted

Replaces #21440
Follows #22861

## Screenshots

### Localized

![image](https://user-images.githubusercontent.com/20454870/230775041-f0af4fda-8f6b-46d3-b8e3-d340c791a50c.png)

![image](https://user-images.githubusercontent.com/20454870/230673393-931415a9-5729-4ac3-9a89-c0fb5fbeeeb7.png)

### Tooltips

#### Native for dates

![image](https://user-images.githubusercontent.com/20454870/230797525-1fa0a854-83e3-484c-9da5-9425ab6528a3.png)

#### Interactive for relative

![image](https://user-images.githubusercontent.com/115237/230796860-51e1d640-c820-4a34-ba2e-39087020626a.png)

### Auto-update

![rec](https://user-images.githubusercontent.com/20454870/230672159-37480d8f-435a-43e9-a2b0-44073351c805.gif)

---------

Signed-off-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: delvh <dev.lh@web.de>

To avoid duplicated load of the same data in an HTTP request, we can set
a context cache to do that. i.e. Some pages may load a user from a
database with the same id in different areas on the same page. But the
code is hidden in two different deep logic. How should we share the
user? As a result of this PR, now if both entry functions accept
`context.Context` as the first parameter and we just need to refactor
`GetUserByID` to reuse the user from the context cache. Then it will not
be loaded twice on an HTTP request.

But of course, sometimes we would like to reload an object from the
database, that's why `RemoveContextData` is also exposed.

The core context cache is here. It defines a new context
```go
type cacheContext struct {
	ctx  context.Context
	data map[any]map[any]any
        lock sync.RWMutex
}

var cacheContextKey = struct{}{}

func WithCacheContext(ctx context.Context) context.Context {
	return context.WithValue(ctx, cacheContextKey, &cacheContext{
		ctx:  ctx,
		data: make(map[any]map[any]any),
	})
}
```

Then you can use the below 4 methods to read/write/del the data within
the same context.

```go
func GetContextData(ctx context.Context, tp, key any) any
func SetContextData(ctx context.Context, tp, key, value any)
func RemoveContextData(ctx context.Context, tp, key any)
func GetWithContextCache[T any](ctx context.Context, cacheGroupKey string, cacheTargetID any, f func() (T, error)) (T, error)
```

Then let's take a look at how `system.GetString` implement it.

```go
func GetSetting(ctx context.Context, key string) (string, error) {
	return cache.GetWithContextCache(ctx, contextCacheKey, key, func() (string, error) {
		return cache.GetString(genSettingCacheKey(key), func() (string, error) {
			res, err := GetSettingNoCache(ctx, key)
			if err != nil {
				return "", err
			}
			return res.SettingValue, nil
		})
	})
}
```

First, it will check if context data include the setting object with the
key. If not, it will query from the global cache which may be memory or
a Redis cache. If not, it will get the object from the database. In the
end, if the object gets from the global cache or database, it will be
set into the context cache.

An object stored in the context cache will only be destroyed after the
context disappeared.

Following
* #21410 

We are now able to localize all timestamps. Some examples:

`short-date` format, French, user profile page:

![image](https://user-images.githubusercontent.com/20454870/195622461-aa0d5b93-f8df-42ad-881c-9c16606bf387.png)

`date-time` format, Portuguese, mirror repository settings page:

![image](https://user-images.githubusercontent.com/20454870/195623191-7a37d77c-4a02-4140-846d-f290a65ea21d.png)

Signed-off-by: Yarden Shoham <hrsi88@gmail.com>

Signed-off-by: Yarden Shoham <hrsi88@gmail.com>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

* Refactor `i18n` to `locale`

- Currently we're using the `i18n` variable naming for the `locale`
struct. This contains locale's specific information and cannot be used
for general i18n purpose, therefore refactoring it to `locale` makes
more sense.
- Ref: https://github.com/go-gitea/gitea/pull/20096#discussion_r906699200

* Update routers/install/install.go

* Direct avatar rendering

This adds new template helpers for avatar rendering which output image
elements with direct links to avatars which makes them cacheable by the
browsers.

This should be a major performance improvment for pages with many avatars.

* fix avatars of other user's profile pages

* fix top border on user avatar name

* uncircle avatars

* remove old incomplete avatar selector

* use title attribute for name and add it back on blame

* minor refactor

* tweak comments

* fix url path join and adjust test to new result

* dedupe functions

Now defaults to 16 on both frontend and backend.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

* Add octicon SVG sprite

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Static prefix

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* SVG for all repo icons

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* make vendor

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Swap out octicons

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Move octicons to top of less imports

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix JS

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Definitely not a search/replace

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Missed regex

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Move to more generic calls and webpack

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* make svg -> make webpack

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Remove svg-sprite

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Update tests

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Missed a test

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Remove svg from makefile

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Suggestions

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Attempt to fix test

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Update tests

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Revert timetracking test

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Swap .octicon for .svg in less

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add aria-hidden

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Replace mega-octicon

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix webpack globbing on Windows

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Revert

Co-Authored-By: silverwind <me@silverwind.io>

* Fix octions from upstream

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix Vue and missed JS function

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add JS helper and PWA

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Preload SVG

Signed-off-by: jolheiser <john.olheiser@gmail.com>

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <matti@mdranta.net>

* refactor struct's time to remove unnecessary memory usage

* use AsTimePtr simple code

* fix tests

* fix time compare

* fix template on gpg

* use AddDuration instead of Add

* Added rel="noopener" to target="_blank" hrefs

* Replaced gogs.io/docs with docs.gitea.io

- User profile un/follow
- List user's followers/following