Separate system operations from core objects in GraphQL endpoints (#12977)

Moves system-level operations (auth, billing, admin) to use the
/metadata endpoint instead of /graphql.

This cleans up the endpoint separation so /graphql is purely for core
objects (Company, People, etc.) and /metadata handles all system
operations.

Part of prep work for webhook/API key core migration.

packages/twenty-front/src/modules/workspace-invitation/hooks/useCreateWorkspaceInvitation.ts

@@ -1,8 +1,8 @@
 import { useSetRecoilState } from 'recoil';
 import {
-  useSendInvitationsMutation,
   SendInvitationsMutationVariables,
-} from '~/generated/graphql';
+  useSendInvitationsMutation,
+} from '~/generated-metadata/graphql';
 import { workspaceInvitationsState } from '../states/workspaceInvitationsStates';
 
 export const useCreateWorkspaceInvitation = () => {