Reusing `/api/v1` from Gitea UI Pages have pros and cons.
Pros:
1) Less code copy

Cons:
1) API/v1 have to support shared session with page requests.
2) You need to consider for each other when you want to change something about api/v1 or page.

This PR moves all dependencies to API/v1 from UI Pages.

Partially replace #16052

Remove two unmaintained vendor packages `i18n` and `paginater`. Changes:
* Rewrite `i18n` package with a more clear fallback mechanism. Fix an unstable `Tr` behavior, add more tests.
* Refactor the legacy `Paginater` to `Paginator`, test cases are kept unchanged.

Trivial enhancement (no breaking for end users):
* Use the first locale in LANGS setting option as the default, add a log to prevent from surprising users.

Adding additional usernames which are already routes, remove unused ones.
In future, avoid reserving names as much as possible, use `/-/` in path instead.

* 2xx/3xx/4xx/5xx -> http.Status...
* http.StatusFound -> http.StatusTemporaryRedirect
* http.StatusMovedPermanently -> http.StatusPermanentRedirect

* Prevent invalid key response.

* Display note instead of 404 response.

* Fixed test.

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

* gofumpt -w -l .

* gofumpt -w -l -extra .

* Add linter

* manual fix

* change make fmt

* Move user related model into models/user

* Fix lint for windows

* Fix windows lint

* Fix windows lint

* Move some tests in models

* Merge

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

* Move db related basic functions to models/db

* Fix lint

* Fix lint

* Fix test

* Fix lint

* Fix lint

* revert unnecessary change

* Fix test

* Fix wrong replace string

* Use *Context

* Correct committer spelling and fix wrong replaced words

Co-authored-by: zeripath <art27@cantab.net>

* Fix data race in testlogger

* Update git_helper_for_declarative_test.go

* fix: add search to reserved usernames

* Update integrations/user_test.go

Co-Authored-By: 6543 <24977596+6543@users.noreply.github.com>

* Test more reserved usernames

* Add more reserved usernames, sort them

* Reserve "attachments" username (is a used route)

* It's "avatars" being reserved, not "avatar"

Signed-off-by: Tamal Saha <tamal@appscode.com>

* add .gpg url (match github behaviour)

* wildcard

* test to export maximum data

* working POC

* add comment for old imported keys

* cleaning

* Update routers/user/profile.go

Co-Authored-By: sapk <sapk@users.noreply.github.com>

* add migration script

* add integration tests

* Ensure valid git author names passed in signatures

Fix #5772 - Git author names are not allowed to include `\n` `<` or `>` and
must not be empty. Ensure that the name passed in a signature is valid.

* Account for pathologically named external users

LDAP and the like usernames are not checked in the same way that users who signup are.
Therefore just ensure that user names are also git safe and if totally pathological -
Set them to "user-$UID"

* Add Tests and adjust test users

Make our testcases a little more pathological so that we be sure that integration
tests have a chance to spot these cases.

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Added user language setting

* Added translation string for setting

* Fixed import order + typo

* improved checking if the user has a language saved in the db

* The current saved language is now set a default inside the dropdown

* fmt

* When a user signs in and doesn't have a language saved, the current browser language is saved

* updated gitea-sdk

* Merge branch 'master' of https://github.com/go-gitea/gitea into save-user-language

# Conflicts:
#	models/migrations/migrations.go
#	models/migrations/v62.go

* Made tests work again

* trigger CI

* trigger CI

* fmt

* re-trigger that FUCKING CI SO IT REALLY PICKS UP THE LATEST COMMIT ISTEAD OF PREDENDING TO DO SO

* re-trigger that FUCKING CI SO IT REALLY PICKS UP THE LATEST COMMIT ISTEAD OF PREDENDING TO DO SO

* When loggin in, only the language col gets updated instead of everything

* Fix missing translations when updating username.

* Fix reserved username translated string test.

* Fix 'username reserved' string test a bit more.

* Helper functions for intergration test boilerplate

* Check for valid renamed usernames

* Integration test

* Test for username with space

* Make name field required

* improve integration test to resue models/fixtures and store git repos with source

* use gitea-integration-meta dir instead .tar.gz and cleanup every before every test

* fix import package name

* Integration test framework

* udpate drone sign

* Formatting fixes and move router.go to routers/

* update sign for drone