[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/generated/graphql.tsx

@@ -1085,7 +1085,7 @@ export type MutationUpdateWorkspaceFeatureFlagArgs = {
 
 
 export type MutationUpdateWorkspaceMemberRoleArgs = {
-  roleId?: InputMaybe<Scalars['String']>;
+  roleId: Scalars['String'];
   workspaceMemberId: Scalars['String'];
 };
 
@@ -2368,7 +2368,7 @@ export type RoleFragmentFragment = { __typename?: 'Role', id: string, label: str
 
 export type UpdateWorkspaceMemberRoleMutationVariables = Exact<{
   workspaceMemberId: Scalars['String'];
-  roleId?: InputMaybe<Scalars['String']>;
+  roleId: Scalars['String'];
 }>;
 
 
@@ -4229,7 +4229,7 @@ export type UpdateLabPublicFeatureFlagMutationHookResult = ReturnType<typeof use
 export type UpdateLabPublicFeatureFlagMutationResult = Apollo.MutationResult<UpdateLabPublicFeatureFlagMutation>;
 export type UpdateLabPublicFeatureFlagMutationOptions = Apollo.BaseMutationOptions<UpdateLabPublicFeatureFlagMutation, UpdateLabPublicFeatureFlagMutationVariables>;
 export const UpdateWorkspaceMemberRoleDocument = gql`
-    mutation UpdateWorkspaceMemberRole($workspaceMemberId: String!, $roleId: String) {
+    mutation UpdateWorkspaceMemberRole($workspaceMemberId: String!, $roleId: String!) {
   updateWorkspaceMemberRole(
     workspaceMemberId: $workspaceMemberId
     roleId: $roleId