MM-52600: [Shared Channels] Shared channels do not sync channel membership (#30976)

server/channels/app/shared_channel_service_iface.go

@@ -26,6 +26,7 @@ type SharedChannelServiceIFace interface {
 	CheckChannelNotShared(channelID string) error
 	CheckChannelIsShared(channelID string) error
 	CheckCanInviteToSharedChannel(channelId string) error
+	HandleMembershipChange(channelID, userID string, isAdd bool, remoteID string)
 }
 
 func NewMockSharedChannelService(service SharedChannelServiceIFace) *mockSharedChannelService {
@@ -91,3 +92,9 @@ func (mrcs *mockSharedChannelService) SendChannelInvite(channel *model.Channel,
 func (mrcs *mockSharedChannelService) NumInvitations() int {
 	return mrcs.numInvitations
 }
+
+func (mrcs *mockSharedChannelService) HandleMembershipChange(channelID, userID string, isAdd bool, remoteID string) {
+	if mrcs.SharedChannelServiceIFace != nil {
+		mrcs.SharedChannelServiceIFace.HandleMembershipChange(channelID, userID, isAdd, remoteID)
+	}
+}