Improve and fix bugs surrounding reactions (#24760)

- Slightly decrease size of reaction buttons
- Remove tooltip inside menu, it's obvious by the picture alone
- Fix top menu triangle
- Use `display: grid` to align icons in menu
- Use regular tooltip for reaction users
- Fix bug that deleted the reaction bar on clicking already reacted
reaction in dropdown

<img width="490" alt="Screenshot 2023-05-17 at 00 03 42"
src="https://github.com/go-gitea/gitea/assets/115237/61588b37-facb-4829-b75b-e1cb5dda8ca4">

<img width="67" alt="Screenshot 2023-05-17 at 00 11 14"
src="https://github.com/go-gitea/gitea/assets/115237/29605589-3b5f-40c6-8ad4-09923094bb8e">

<img width="211" alt="Screenshot 2023-05-17 at 00 29 30"
src="https://github.com/go-gitea/gitea/assets/115237/7d2725da-6a3d-4e42-a351-53647f79f762">
<img width="210" alt="Screenshot 2023-05-17 at 00 29 54"
src="https://github.com/go-gitea/gitea/assets/115237/b50f8364-033c-4445-ba25-61a814bb2d92">


<img width="892" alt="Screenshot 2023-05-17 at 00 12 20"
src="https://github.com/go-gitea/gitea/assets/115237/30a46424-406a-46e5-b4de-47172eb8679d">

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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>

templates/repo/issue/view_content/add_reaction.tmpl

@@ -1,13 +1,11 @@
 {{if .ctxData.IsSigned}}
 <div class="item action ui dropdown jump pointing top right select-reaction" data-action-url="{{.ActionURL}}">
-	<a class="add-reaction">
+	<a class="add-reaction muted">
 		{{svg "octicon-smiley"}}
 	</a>
-	<div class="menu">
-		<div class="header">{{.ctxData.locale.Tr "repo.pick_reaction"}}</div>
-		<div class="divider"></div>
+	<div class="menu reactions-menu">
 		{{range $value := AllowedReactions}}
-			<a class="item reaction" data-tooltip-content="{{$value}}" data-reaction-content="{{$value}}">{{ReactionToEmoji $value}}</a>
+			<a class="item reaction" data-tooltip-content="{{$value}}" aria-label="{{$value}}" data-reaction-content="{{$value}}">{{ReactionToEmoji $value}}</a>
 		{{end}}
 	</div>
 </div>