Autocreate some local accounts when global account is created

Add $wgCentralAuthAutoCreateWikis site config option;
run a job on global account creation to create an attached
local account on all listed wikis.

Bug: T74469
Bug: T94885
Bug: T85703
Change-Id: I3937b9e6d0df1ef608d64388167a3b37a3ea5de3