To Implement new Role Assignments tab for specific group
as it is done for Users, this is about to include RoleAssignmentList component, based on the role assignments related with specific group

Things to consider:

• subject column should be hidden. use/extend "hiddenColumns" see https://github.com/stolostron/console/blob/e581ae3a0315697be61c79cd9781eef1c9e601fb/frontend/src/routes/UserManagement/RoleAssignment/RoleAssignments.tsx#L30