[native] Pull CommunityCreationKeyserverLabel out of CommunityConfiguration

Summary:
noop, just so we can include CommunityCreationKeyserverLabel in CommunityCreationMembers (next diff(s)).

Depends on D7987

Test Plan: Everything looks exactly as before, cut/paste

Reviewers: ashoat, ginsu

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D7988