Remove htmx (#37224)

Close #35059

Slightly improved the "fetch action" framework and started adding tests for it.

---------

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

templates/repo/view_list.tmpl

@@ -3,7 +3,7 @@
 	{{if .HasFilesWithoutLatestCommit}}
 		data-fetch-url="{{.LastCommitLoaderURL}}"
 		data-fetch-trigger="load" data-fetch-sync="$morph"
-		data-fetch-indicator="#repo-files-table .repo-file-cell.notready.message"
+		data-fetch-indicator=".repo-file-cell.notready.message"
 	{{end}}
 >
 	<div class="repo-file-line repo-file-last-commit">