Str2html was abused a lot. So use a proper name for it: SanitizeHTML

And add some tests to show its behavior.

Follow #24393


The funny history:

* At the beginning, `.ui.message` was polluted by `text-align: center`
* Then people do `<div class="ui ... message text left">`
* But `.ui.left` is polluted by `float: left`
* Then people do `#xxx .ui.message { width: 100% !important;}`

The code just becomes more and more hacky.

After removing the pollution,  everything becomes clear and straight.


And, this PR also does:

1. Remove the `package.css`, its styles could be provided by `top
aligned`
2. Remove `#avatar-arrow`, dead code



Screenshot:


![image](https://user-images.githubusercontent.com/2114189/235862130-a9eb5d8f-7d01-457c-99f7-21d0abc3075e.png)


![image](https://user-images.githubusercontent.com/2114189/235862222-139709a7-95c2-4f89-a40f-100b2d76d9bb.png)

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

* feat: extend issue template for yaml

* feat: support yaml template

* feat: render form to markdown

* feat: support yaml template for pr

* chore: rename to Fields

* feat: template unmarshal

* feat: split template

* feat: render to markdown

* feat: use full name as template file name

* chore: remove useless file

* feat: use dropdown of fomantic ui

* feat: update input style

* docs: more comments

* fix: render text without render

* chore: fix lint error

* fix: support use description as about in markdown

* fix: add field class in form

* chore: generate swagger

* feat: validate template

* feat: support is_nummber and regex

* test: fix broken unit tests

* fix: ignore empty body of md template

* fix: make multiple easymde editors work in one page

* feat: better UI

* fix: js error in pr form

* chore: generate swagger

* feat: support regex validation

* chore: generate swagger

* fix: refresh each markdown editor

* chore: give up required validation

* fix: correct issue template candidates

* fix: correct checkboxes style

* chore: ignore .hugo_build.lock in docs

* docs: separate out a new doc for merge templates

* docs: introduce syntax of yaml template

* feat: show a alert for invalid templates

* test: add case for a valid template

* fix: correct attributes of required checkbox

* fix: add class not-under-easymde for dropzone

* fix: use more back-quotes

* chore: remove translation in zh-CN

* fix EasyMDE statusbar margin

* fix: remove repeated blocks

* fix: reuse regex for quotes

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

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

commit 0afcb843d7
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 17:13:29 2016 -0600

    Removed Upload stats as the upload table is just a temporary table

commit 7ecd73ff55
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 08:42:41 2016 -0600

    Fix for CodeMirror mode

commit c29b9ab531
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 08:03:33 2016 -0600

    Made tabbing in editor use spaces

commit 23af384c53
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:56:46 2016 -0600

    Fix for data-url

commit cfb8a97591
Merge: 7fc8a89 991ce42
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:42:53 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	public/js/gogs.js

commit 7fc8a89cb4
Merge: fd3d86c c03d040
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:40:00 2016 -0600

    Merge branch 'feature-create-and-edit-repo-file' of github.com:richmahn/gogs into feature-create-and-edit-repo-file

commit fd3d86ca6b
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:39:44 2016 -0600

    Code cleanup

commit c03d0401c1
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 29 15:38:23 2016 -0600

    Code cleanup

commit 98e1206ccf
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 18:36:01 2016 -0600

    Code cleanup and fixes

commit c2895dc742
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 18:24:04 2016 -0600

    Fixes per Unknwon's requests

commit 6aa7e46b21
Merge: 889e9fa ad7ea88
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 17:13:43 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	modules/setting/setting.go

commit 889e9faf1b
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:09:18 2016 -0600

    Fix in gogs.js

commit 47603edf22
Merge: bb57912 cf85e9e
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:07:36 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	public/js/gogs.js

commit bb57912558
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:02:18 2016 -0600

    Update for using CodeMirror mode addon

commit d10d128c51
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Tue Jul 19 16:12:57 2016 -0600

    Update for Edit

commit 34a3498202
Merge: fa1b752 1c7dcdd
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Tue Jul 19 11:52:02 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go

commit fa1b752be2
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 15 18:35:42 2016 -0600

    Feature for editing, creating, uploading and deleting files

This commit improves templates readability, since all of them use consistent
indent with all template command blocks indented too.

1. Indents both HTML containers such as <div>, <p> and Go HTML template blocks
   such as {{if}} {{with}}

2. Cleans all trailing white-space

3. Adds trailing last line-break to each file

- fix update lable break connection with repository