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/editor/patch.tmpl

@@ -22,7 +22,7 @@
 			<div class="field">
 				<div class="ui top attached header">
 					<div class="flex-text-block tw-justify-between tw-flex-wrap">
-						<div class="ui compact small menu small-menu-items repo-editor-menu tw-self-start">
+						<div class="ui compact small menu small-menu-items repo-editor-menu">
 							<a class="active item" data-tab="write">{{svg "octicon-code" 16 "tw-mr-1"}}{{ctx.Locale.Tr "repo.editor.new_patch"}}</a>
 						</div>
 						{{template "repo/editor/options" dict "CodeEditorConfig" $.CodeEditorConfig}}