[permissions] Update updateRole logic + disallow self role-assignment (#10476)

In this PR

- updateWorkspaceMemberRole api was changed to stop allowing null as a
valid value for roleId. it is not possible anymore to just unassign a
role from a user. instead it is only possible to assign a different role
to a user, which will unassign them from their previous role. For this
reason in the FE the bins icons next to the workspaceMember on a role
page were removed
- updateWorkspaceMemberRole will throw if a user attempts to update
their own role
- tests tests tests!

packages/twenty-front/src/modules/settings/roles/graphql/mutations/updateWorkspaceMemberRoleMutation.ts

@@ -7,7 +7,7 @@ export const UPDATE_WORKSPACE_MEMBER_ROLE = gql`
   ${ROLE_FRAGMENT}
   mutation UpdateWorkspaceMemberRole(
     $workspaceMemberId: String!
-    $roleId: String
+    $roleId: String!
   ) {
     updateWorkspaceMemberRole(
       workspaceMemberId: $workspaceMemberId