Move helpers to be prefixed with gt- (#22879)

As discussed in #22847 the helpers in helpers.less need to have a
separate prefix as they are causing conflicts with fomantic styles

This will allow us to have the `.gt-hidden { display:none !important; }`
style that is needed to for the reverted PR.

Of note in doing this I have noticed that there was already a conflict
with at least one chroma style which this PR now avoids.

I've also added in the `gt-hidden` style that matches the tailwind one
and switched the code that needed it to use that.

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

---------

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/repo/wiki/revision.tmpl

@@ -4,7 +4,7 @@
 	{{$title := .title}}
 	<div class="ui container">
 		<div class="ui stackable grid">
-			<div class="ui eight wide column text right df ac je">
+			<div class="ui eight wide column text right gt-df gt-ac gt-je">
 				<div class="ui action small input" id="clone-panel">
 					{{template "repo/clone_buttons" .}}
 					{{template "repo/clone_script" .}}
@@ -13,7 +13,7 @@
 			<div class="ui header eight wide column">
 				<a class="file-revisions-btn ui basic button" title="{{.locale.Tr "repo.wiki.back_to_wiki"}}" href="{{.RepoLink}}/wiki/{{.PageURL}}" ><span>{{.revision}}</span> {{svg "octicon-home"}}</a>
 				{{$title}}
-				<div class="ui sub header word-break">
+				<div class="ui sub header gt-word-break">
 					{{$timeSince := TimeSince .Author.When $.locale}}
 					{{.locale.Tr "repo.wiki.last_commit_info" .Author.Name $timeSince | Safe}}
 				</div>