p4 add repo username/password ignored unless "show advanced settings" is checked.

To reproduce:

1. add p4 repo with an invalid username/password (e.g. "baduser")
2. leave the "show advanced settings" checkbox unchecked
3. hit "test connection"

Excpected:
test connection log should show "-u baduser" on p4 command line

Actual:
test connection log does not pass "-u baduser" on p4 command line

Workaround:
when adding a p4 repo, check the "show advanced settings" checkbox before testing connection or saving.

Diagnosis:
username & password fields incorrectly grouped in PerforceRepositoryDetails.AdvancedOptions