Ping new shared channels remotes immediately (#25850)

* option for auto inviting plugin to all shared channels.

* auto-invite remotes to shared channels when flag set

* fix unit test

* immediately ping new remotes; fix unique siteurl bug

* make i18n-extract

* fix translations

* fix merge conflicts

* make modules-tidy

* revert accidental go.mod change

* revert accidental go.sum changes

---------

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

server/platform/services/remotecluster/service.go

@@ -70,6 +70,8 @@ type RemoteClusterServiceIFace interface {
 	SendProfileImage(ctx context.Context, userID string, rc *model.RemoteCluster, provider ProfileImageProvider, f SendProfileImageResultFunc) error
 	AcceptInvitation(invite *model.RemoteClusterInvite, name string, displayName string, creatorId string, teamId string, siteURL string) (*model.RemoteCluster, error)
 	ReceiveIncomingMsg(rc *model.RemoteCluster, msg model.RemoteClusterMsg) Response
+	ReceiveInviteConfirmation(invite model.RemoteClusterInvite) (*model.RemoteCluster, error)
+	PingNow(rc *model.RemoteCluster)
 }
 
 // TopicListener is a callback signature used to listen for incoming messages for