Use git diff-tree for DiffFileTree on diff pages (#33514)

Modify Diff View FileTree to show all files

## Changes

* removes Show Status button on diff
* uses `git diff-tree` to generate the file tree for the diff
* doesn't reload the diff tree each time we load more files in the
preview
* selecting and unloaded file will keep loading until that file is
loaded
* removes `DiffFileList.vue` and "Show Stats" in diff options

## Open Questions

* selecting and unloaded file will keep loading until that file is
loaded. Is this behaviour okay? It matches what github does.

### Demo

In this demo I set `git.MAX_GIT_DIFF_FILES=1` in my `app.ini` to
demonstrate a worst case example. In most cases the behaviour isn't
nearly as jarring as we load a bunch of files at a time.


https://github.com/user-attachments/assets/72f29663-d6fc-472d-94fa-7fb5950c2836

---------

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

templates/repo/diff/options_dropdown.tmpl

@@ -1,7 +1,6 @@
 <div class="ui dropdown tiny basic button" data-tooltip-content="{{ctx.Locale.Tr "repo.diff.options_button"}}">
 	{{svg "octicon-kebab-horizontal"}}
 	<div class="menu">
-		<a class="item" id="show-file-list-btn">{{ctx.Locale.Tr "repo.diff.show_diff_stats"}}</a>
 		{{if .Issue.Index}}
 			<a class="item" href="{{$.RepoLink}}/pulls/{{.Issue.Index}}.patch" download="{{.Issue.Index}}.patch">{{ctx.Locale.Tr "repo.diff.download_patch"}}</a>
 			<a class="item" href="{{$.RepoLink}}/pulls/{{.Issue.Index}}.diff" download="{{.Issue.Index}}.diff">{{ctx.Locale.Tr "repo.diff.download_diff"}}</a>