[EC-387] Don't count revoked users towards occupied seat count (#2256)

Also autoscale seats when restoring user if required

src/Core/Services/IOrganizationService.cs

@@ -64,4 +64,5 @@ public interface IOrganizationService
     Task RestoreUserAsync(OrganizationUser organizationUser, Guid? restoringUserId, IUserService userService);
     Task<List<Tuple<OrganizationUser, string>>> RestoreUsersAsync(Guid organizationId,
         IEnumerable<Guid> organizationUserIds, Guid? restoringUserId, IUserService userService);
+    Task<int> GetOccupiedSeatCount(Organization organization);
 }