"Mute conversation" option on all own toots, not just in notifications (#4844)

That way you can mute notifications for a toot before you get replies
to it or boosts or favourites

app/javascript/mastodon/components/status_action_bar.js

@@ -134,7 +134,7 @@ export default class StatusActionBar extends ImmutablePureComponent {
 
     menu.push(null);
 
-    if (withDismiss) {
+    if (status.getIn(['account', 'id']) === me || withDismiss) {
       menu.push({ text: intl.formatMessage(mutingConversation ? messages.unmuteConversation : messages.muteConversation), action: this.handleConversationMuteClick });
       menu.push(null);
     }