[roles_add_groups] updated visibility for "Add Groups"

[Jeff-Rowell]

Summary

Previously the Add Groups and Add Owner Groups buttons on a role page were gated by isAccessAdmin, hiding them from role owners who weren't also Access admins.

• Visibility is now isAccessAdmin || (role owner who owns ≥1 non-role group).
• For non-admins, the dialog's autocomplete is restricted to groups the user owns, and an info note explains that unowned groups must be added via a role request from the group's page.
• This brings the role page in parity with the group page, where AddRoles already permits group owners (not just admins).

Testing

• Locally stubbed isAccessAdmin to return false to simulate a non-admin role owner.

• As role owner of Role-JeffTestRole who owns multiple groups, both buttons appear, the dialog shows the info note, and the autocomplete only lists owned groups.