UX: prevents long press on reaction to open actions (#20899)

This is super hard to write a test as a combination of: long press, mobile and popup.

plugins/chat/assets/javascripts/discourse/components/chat-message-reaction.hbs

@@ -1,6 +1,7 @@
 {{#if (and @reaction this.emojiUrl)}}
   <button
     type="button"
+    {{on "touchstart" this.handleTouchStart}}
     {{on "click" this.handleClick}}
     tabindex="0"
     class={{concat-class

plugins/chat/assets/javascripts/discourse/components/chat-message-reaction.js

@@ -45,6 +45,11 @@ export default class ChatMessageReaction extends Component {
     return emojiUrlFor(this.args.reaction.emoji);
   }
 
+  @action
+  handleTouchStart(event) {
+    event.stopPropagation();
+  }
+
   @action
   handleClick() {
     this.args.react?.(