PLT-5458: If someone posts a channel link to channel_A that you don't belong to, it doesn't render properly (#7833)

* add channel link hints to post props

* optimization

* update regex, add unit test

* fix rebase issue

store/store.go

@@ -119,6 +119,7 @@ type ChannelStore interface {
 	PermanentDeleteByTeam(teamId string) StoreChannel
 	PermanentDelete(channelId string) StoreChannel
 	GetByName(team_id string, name string, allowFromCache bool) StoreChannel
+	GetByNames(team_id string, names []string, allowFromCache bool) StoreChannel
 	GetByNameIncludeDeleted(team_id string, name string, allowFromCache bool) StoreChannel
 	GetDeletedByName(team_id string, name string) StoreChannel
 	GetDeleted(team_id string, offset int, limit int) StoreChannel