Quote a mention as text when replying

Replying swaps each mention in the quoted copy for its text. Assigning
that text to outerHTML parsed it as html; replace the mention with a
text node instead.

(cherry picked from commit 6052b123d5)

app/javascript/controllers/reply_controller.js

@@ -28,7 +28,7 @@ export default class extends Controller {
   }
 
   #stripMentionAttachments(node) {
-    node.querySelectorAll(".mention").forEach(mention => mention.outerHTML = mention.textContent.trim())
+    node.querySelectorAll(".mention").forEach(mention => mention.replaceWith(mention.textContent.trim()))
     return node
   }