[MM-59361] custom groups & read only channels (#28892)

* added group mention, read only view and post event tracking

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/store/retrylayer/retrylayer.go

@@ -2252,6 +2252,48 @@ func (s *RetryLayerChannelStore) InvalidatePinnedPostCount(channelID string) {
 
 }
 
+func (s *RetryLayerChannelStore) IsChannelReadOnlyScheme(schemeID string) (bool, error) {
+
+	tries := 0
+	for {
+		result, err := s.ChannelStore.IsChannelReadOnlyScheme(schemeID)
+		if err == nil {
+			return result, nil
+		}
+		if !isRepeatableError(err) {
+			return result, err
+		}
+		tries++
+		if tries >= 3 {
+			err = errors.Wrap(err, "giving up after 3 consecutive repeatable transaction failures")
+			return result, err
+		}
+		timepkg.Sleep(100 * timepkg.Millisecond)
+	}
+
+}
+
+func (s *RetryLayerChannelStore) IsReadOnlyChannel(channelID string) (bool, error) {
+
+	tries := 0
+	for {
+		result, err := s.ChannelStore.IsReadOnlyChannel(channelID)
+		if err == nil {
+			return result, nil
+		}
+		if !isRepeatableError(err) {
+			return result, err
+		}
+		tries++
+		if tries >= 3 {
+			err = errors.Wrap(err, "giving up after 3 consecutive repeatable transaction failures")
+			return result, err
+		}
+		timepkg.Sleep(100 * timepkg.Millisecond)
+	}
+
+}
+
 func (s *RetryLayerChannelStore) MigrateChannelMembers(fromChannelID string, fromUserID string) (map[string]string, error) {
 
 	tries := 0