[Catalog] Ability to delete purchaser's claimed seats

Problem statement:

Currently, there is no option for a Catalog root admin or subcatalog admin to view a purchaser's claimed seats (see related idea: [Catalog] Allow Catalog admins to have access and ... - Instructure Community - 576411 ). If a purchaser claimed seats that they realize they won't be able to use and request an admin for a refund, the admin cannot take back or delete the refunded seat.

Proposed solution:

Allow admins to be able to see purchasers in their catalog (and the root admins to see/manage all claimed seats for all subcatalogs) and provide the ability to remove/delete claimed seats.

User role(s):

admin