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>

routers/web/repo/blame.go

@@ -262,9 +262,9 @@ func renderBlame(ctx *context.Context, blameParts []git.BlamePart, commitNames m
 
 				var avatar string
 				if commit.User != nil {
-					avatar = string(templates.Avatar(commit.User, 18, "mr-3"))
+					avatar = string(templates.Avatar(commit.User, 18, "gt-mr-3"))
 				} else {
-					avatar = string(templates.AvatarByEmail(commit.Author.Email, commit.Author.Name, 18, "mr-3"))
+					avatar = string(templates.AvatarByEmail(commit.Author.Email, commit.Author.Name, 18, "gt-mr-3"))
 				}
 
 				br.Avatar = gotemplate.HTML(avatar)

routers/web/repo/issue_content_history.go

@@ -71,7 +71,7 @@ func GetContentHistoryList(ctx *context.Context) {
 		}
 
 		src := html.EscapeString(item.UserAvatarLink)
-		class := avatars.DefaultAvatarClass + " mr-3"
+		class := avatars.DefaultAvatarClass + " gt-mr-3"
 		name := html.EscapeString(username)
 		avatarHTML := string(templates.AvatarHTML(src, 28, class, username))
 		timeSinceText := string(timeutil.TimeSinceUnix(item.EditedUnix, ctx.Locale))