This filter should make usages of forward_from and forward_from_chat in order to filter out messages which get forwarded by a certain chat.

This should inherit from _ChatUserBaseFilter, Filters.user or Filters.sender_chat are example implementations of this.

You can either create a new Filter like Filters.forwarded_by or you can enhance Filters.forwarded (behaviour could be copied from Filters.chat_type). I would prefer the second option in order to reduce the overall numbers of filters, other maintainers?