MM-23596: Ability to list private channels for team (#14925)

Summary:
store, app, api and go driver support for listing private channels

Ticket Link:
https://mattermost.atlassian.net/browse/MM-23596

api4/channel_local.go

@@ -24,6 +24,7 @@ func (api *API) InitChannelLocal() {
 
 	api.BaseRoutes.ChannelsForTeam.Handle("", api.ApiLocal(getPublicChannelsForTeam)).Methods("GET")
 	api.BaseRoutes.ChannelsForTeam.Handle("/deleted", api.ApiLocal(getDeletedChannelsForTeam)).Methods("GET")
+	api.BaseRoutes.ChannelsForTeam.Handle("/private", api.ApiLocal(getPrivateChannelsForTeam)).Methods("GET")
 
 	api.BaseRoutes.ChannelByName.Handle("", api.ApiLocal(getChannelByName)).Methods("GET")
 	api.BaseRoutes.ChannelByNameForTeamName.Handle("", api.ApiLocal(getChannelByNameForTeamName)).Methods("GET")