Add non-JS fallback for reaction tooltips (#28785)

When JavaScript is not loaded, fall back to displaying reaction tooltips
with the default browser `title` attribute. An element with a present
but empty `data-tooltip-content` will use the `title` attribute for its
tippy.js tooltip content, so when JavaScript is enabled, this functions
the same as the current behavior.

templates/repo/issue/view_content/reactions.tmpl

@@ -2,7 +2,9 @@
 {{range $key, $value := .Reactions}}
 	{{$hasReacted := $value.HasUser $.ctxData.SignedUserID}}
 	<a role="button" class="ui label basic{{if $hasReacted}} primary{{end}}{{if not $.ctxData.IsSigned}} disabled{{end}} comment-reaction-button"
-		data-tooltip-content="{{$value.GetFirstUsers}}{{if gt ($value.GetMoreUserCount) 0}} {{ctx.Locale.Tr "repo.reactions_more" $value.GetMoreUserCount}}{{end}}"
+		data-tooltip-content
+		title="{{$value.GetFirstUsers}}{{if gt ($value.GetMoreUserCount) 0}} {{ctx.Locale.Tr "repo.reactions_more" $value.GetMoreUserCount}}{{end}}"
+		aria-label="{{$value.GetFirstUsers}}{{if gt ($value.GetMoreUserCount) 0}} {{ctx.Locale.Tr "repo.reactions_more" $value.GetMoreUserCount}}{{end}}"
 		data-tooltip-placement="bottom-start"
 		data-reaction-content="{{$key}}" data-has-reacted="{{$hasReacted}}">
 		<span class="reaction">{{ReactionToEmoji $key}}</span>