Make Special:CentralAuth list local accounts in all cases

Even if there's no global account for them.
Also declared visibility on everything in there to make the
code a little less bad.
This should bring future parity with the popular "sulutil".

Bug: 53919
Bug: 53898
Change-Id: Ib508f7814a6a3984b5d2a6e4b6bf7eb6508eb220
Merge "Make Special:CentralAuth list local accounts in all cases"