Groups: add a third option for group type, invitation only.

[yoyopuyo]

Groups has a bool to tell if it's open or close. However there is a third common option in games: the guild is completely closed and you can only join with an invitation.
This is made a bit harder to add as the "Open" is a bool right now.
Maybe a GroupType variable with three options.

Thank you.

[einfachBlu]

Is there currently any other workaround to invite users to a group and when they accept, that they join the group?
Currently i thought about saving a group invite in their user storage and when they click "accept" in the game it should add him. But they cannot add themself to the group. is there a solid workaround or how other games solved that with nakama?