Shared channels plugin APIs for MS Teams plugin (#25805)

New plugin APIs and hooks for accessing Shared Channels service via plugin. 

- RegisterPluginForSharedChannels(opts model.RegisterPluginOpts) (remoteID string, err error)
- UnregisterPluginForSharedChannels(pluginID string) error
- ShareChannel(sc *model.SharedChannel) (*model.SharedChannel, error)
- UpdateSharedChannel(sc *model.SharedChannel) (*model.SharedChannel, error)
- UnshareChannel(channelID string) (unshared bool, err error)
- UpdateSharedChannelCursor(channelID, remoteID string, cusror model.GetPostsSinceForSyncCursor) error
- SyncSharedChannel(channelID string) error
- InviteRemoteToChannel(channelID string, remoteID string, userID string) error
- UninviteRemoteFromChannel(channelID string, remoteID string) error

Hooks
- OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error)
- OnSharedChannelsPing(rc *model.RemoteCluster) bool

server/public/plugin/hooks_timer_layer_generated.go

@@ -250,3 +250,17 @@ func (hooks *hooksTimerLayer) ServeMetrics(c *Context, w http.ResponseWriter, r
 	hooks.hooksImpl.ServeMetrics(c, w, r)
 	hooks.recordTime(startTime, "ServeMetrics", true)
 }
+
+func (hooks *hooksTimerLayer) OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error) {
+	startTime := timePkg.Now()
+	_returnsA, _returnsB := hooks.hooksImpl.OnSharedChannelsSyncMsg(msg, rc)
+	hooks.recordTime(startTime, "OnSharedChannelsSyncMsg", _returnsB == nil)
+	return _returnsA, _returnsB
+}
+
+func (hooks *hooksTimerLayer) OnSharedChannelsPing(rc *model.RemoteCluster) bool {
+	startTime := timePkg.Now()
+	_returnsA := hooks.hooksImpl.OnSharedChannelsPing(rc)
+	hooks.recordTime(startTime, "OnSharedChannelsPing", true)
+	return _returnsA
+}