Refactor IsStaff from RT::Condition::RTIR into RT::IR

This allows other code to make decisions based on membership in a
DutyTeam
Other DutyTeam code ignores case, do the same
If this user is a DutyTeam member, send them to /RTIR/

If they specify anything other than / they'll be sent there instead.

Resolves issues #30334
RedirectOnLogin config

To disable the new "DutyTeam members redirect to /RTIR/" feature
Merge branch '3.2/redirect-on-login'