Backport #28942 by @Zettat123

In #28691, schedule plans will be deleted when a repo's actions unit is
disabled. But when the unit is enabled, the schedule plans won't be
created again.

This PR fixes the bug. The schedule plans will be created again when the
actions unit is re-enabled

---------

Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Close #7570


1. Clearly define the wiki path behaviors, see
`services/wiki/wiki_path.go` and tests
2. Keep compatibility with old contents
3. Allow to use dashes in titles, eg: "2000-01-02 Meeting record"
4. Add a "Pages" link in the dropdown, otherwise users can't go to the
Pages page easily.
5. Add a "View original git file" link in the Pages list, even if some
file names are broken, users still have a chance to edit or remove it,
without cloning the wiki repo to local.
6. Fix 500 error when the name contains prefix spaces.


This PR also introduces the ability to support sub-directories, but it
can't be done at the moment due to there are a lot of legacy wiki data,
which use "%2F" in file names.



![image](https://user-images.githubusercontent.com/2114189/232239004-3359d7b9-7bf3-4ff3-8446-bfb0e79645dd.png)


![image](https://user-images.githubusercontent.com/2114189/232239020-74b92c72-bf73-4377-a319-1c85609f82b1.png)

Co-authored-by: Giteabot <teabot@gitea.io>

Addition to #22256

The `convert` package relies heavily on different models which is
[disallowed by our definition of
modules](https://github.com/go-gitea/gitea/blob/main/CONTRIBUTING.md#design-guideline).
This helps to prevent possible import cycles.

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

Change all license headers to comply with REUSE specification.

Fix #16132

Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>

* Some refactors related repository model

* Move more methods out of repository

* Move repository into models/repo

* Fix test

* Fix test

* some improvements

* Remove unnecessary function

* Add API to get/edit wiki

* Add swagger docs, various improvements

* fmt

* Fix lint and rm comment

* Add page parameter

* Add pagination to pages

* Add tests

* fmt

* Update func names

* Update error handling

* Update type name

* Fix lint

* Don't delete Home

* Update func name

* Update routers/api/v1/repo/wiki.go

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

* Remove unnecessary check

* Fix lint

* Use English strings

* Update integrations/api_wiki_test.go

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

* Update func and test names

* Remove unsed check and avoid duplicated error reports

* Improve error handling

* Return after error

* Document 404 error

* Update swagger

* Fix lint

* Apply suggestions from code review

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

* Document file encoding

* fmt

* Apply suggestions

* Use convert

* Fix integration test

* simplify permissions

* unify duplicate key Title/Name

* improve types & return UTC timestamps

* improve types pt.2

- add WikiPageMetaData.LastCommit
- add WikiPageMetaData.HTMLURL
- replace WikiPageMetaData.Updated with .LastCommit.Committer.Created

also delete convert.ToWikiPage(), as it received too many arguments and
only had one callsite anyway. sorry for bad advice earlier 🙃

* WikiPage.Content is base64 encoded

* simplify error handling in wikiContentsByName()

* update swagger

* fix & DRY findWikiRepoCommit() error handling

ListWikiPages() previously wrote error twice when repo wiki didn't exist

* rename Content -> ContentBase64

* Fix test

* Fix tests

* Update var name

* suburl -> sub_url

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Norwin <git@nroo.de>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>