Merge branch 'rm/346575' into 'master'

add join button in thread instead of readonly message

See merge request kchat/webapp!868

webapp/channels/src/components/advanced_text_editor/advanced_text_editor.tsx

@@ -13,9 +13,11 @@ import type {ServerError} from '@mattermost/types/errors';
 import type {FileInfo} from '@mattermost/types/files';
 import type {Post} from '@mattermost/types/posts';
 
+import * as GlobalActions from 'actions/global_actions';
 import {emitShortcutReactToLastPostFrom} from 'actions/post_actions';
 import LocalStorageStore from 'stores/local_storage_store';
 
+import {BannerJoinChannel} from 'components/banner_join_channel';
 import AutoHeightSwitcher from 'components/common/auto_height_switcher';
 import DndBanner from 'components/dnd_banner';
 import EmojiPickerOverlay from 'components/emoji_picker/emoji_picker_overlay';
@@ -714,6 +716,12 @@ const AdvanceTextEditor = ({
         />
     );
 
+    if (readOnlyChannel) {
+        return (
+            <BannerJoinChannel onButtonClick={() => GlobalActions.joinChannel(channelId)}/>
+        );
+    }
+
     return (
         <>
             <div