APIv4 GET /users/{user_id}/posts/flagged (#5984)

* APIv4 GET /users/{user_id}/posts/flagged

* change permission check

store/store.go

@@ -150,6 +150,7 @@ type PostStore interface {
 	GetPosts(channelId string, offset int, limit int, allowFromCache bool) StoreChannel
 	GetFlaggedPosts(userId string, offset int, limit int) StoreChannel
 	GetFlaggedPostsForTeam(userId, teamId string, offset int, limit int) StoreChannel
+	GetFlaggedPostsForChannel(userId, channelId string, offset int, limit int) StoreChannel
 	GetPostsBefore(channelId string, postId string, numPosts int, offset int) StoreChannel
 	GetPostsAfter(channelId string, postId string, numPosts int, offset int) StoreChannel
 	GetPostsSince(channelId string, time int64, allowFromCache bool) StoreChannel