feat(auth): Revamp authentication setup (#7387)

* chore: Clean up authentication middlewares

* chore: Rename AuthUser to AuthIdentity

* feat: Define link between user, customer, and auth identity

* feat: Use links for auth, update auth context content

* fix: Adjust user create command with new auth setup

* fix: Make auth login more dynamic, review fixes

* fix: Change test assertions for created by

packages/medusa/src/api/admin/customers/route.ts

@@ -48,7 +48,7 @@ export const POST = async (
   const customersData = [
     {
       ...req.validatedBody,
-      created_by: req.auth?.actor_id,
+      created_by: req.auth_context.actor_id,
     },
   ]