feat(medusa,types,core-flows): apply created_by values - claims, exchanges, returns, fulfillment (#8712)

what:

- Applies created_by values - claims, exchanges, returns, fulfillment

RESOLVES CC-96

integration-tests/modules/__tests__/fulfillment/index.spec.ts

@@ -156,6 +156,7 @@ medusaIntegrationTestRunner({
             shipped_at: null,
             delivered_at: null,
             canceled_at: null,
+            created_by: expect.any(String),
             provider_id: "manual_test-provider",
             delivery_address: expect.objectContaining({
               address_1: expect.any(String),
@@ -240,6 +241,7 @@ medusaIntegrationTestRunner({
           expect.objectContaining({
             id: fulfillment.id,
             shipped_at: expect.any(String),
+            marked_shipped_by: expect.any(String),
             labels: [
               expect.objectContaining({
                 id: expect.any(String),