* Server-side syntax hilighting for all code

This PR does a few things:

* Remove all traces of highlight.js
* Use chroma library to provide fast syntax hilighting directly on the server
* Provide syntax hilighting for diffs
* Re-style both unified and split diffs views
* Add custom syntax hilighting styling for both regular and arc-green

Fixes #7729
Fixes #10157
Fixes #11825
Fixes #7728
Fixes #3872
Fixes #3682

And perhaps gets closer to #9553

* fix line marker

* fix repo search

* Fix single line select

* properly load settings

* npm uninstall highlight.js

* review suggestion

* code review

* forgot to call function

* fix test

* Apply suggestions from code review

suggestions from @silverwind thanks

Co-authored-by: silverwind <me@silverwind.io>

* code review

* copy/paste error

* Use const for highlight size limit

* Update web_src/less/_repository.less

Co-authored-by: Lauris BH <lauris@nix.lv>

* update size limit to 1MB and other styling tweaks

* fix highlighting for certain diff sections

* fix test

* add worker back as suggested

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lauris BH <lauris@nix.lv>

Fomantic-ui's action button syntax requires that the button is
the next sibling of the input it is attached to and that they
are both children of a div.action.

Fix #11375

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

Co-authored-by: Lauris BH <lauris@nix.lv>

change status icon for merged PR to git-merge

Signed-off-by: a101211279 <1012112796@qq.com>

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Fixed wrong AppSubUrl in OAuth2 app edit page

* Replaced all other occurrences of $.AppSubURL for support of sub-paths

Move langauge detection to separate module to be more reusable

Add option to disable vendored file exclusion from file search

Allways show all language stats for search

The choice regarding which forms should or should not trigger a warning
is subjective. I tried to be consistent and not warn about forms that:
 - run an action, rather than edit data: search, send an email.
 - delete data: a warning about losing data would be confusing

Note that forms on sign-in pages were already ignored (using a selector,
rather than an explicit class on the form element).

Fixes #3698.

* add global code search on explore

* fix bug when no anyone public repos

* change the icon

* fix typo and add UnitTypeCode check for login non-admin user

* fix ui description when no match