refactor: 💡 Add worker_filter to vault credential stores (#1310)

* refactor: 💡 Add worker_filter to vault credential stores

Add worker_filter attribute to vault type credential store model

✅ Closes: ICU-5988

* refactor: 💡 Add worker_filter mirage mock for credential store (#1312)

✅ Closes: ICU-5990

addons/api/addon/generated/models/credential-store.js

@@ -117,4 +117,12 @@ export default class GeneratedCredentialStoreModel extends BaseModel {
     readOnly: true,
   })
   client_certificate_key_hmac;
+
+  @attr('string', {
+    for: 'vault',
+    isNestedAttribute: true,
+    description:
+      'Filters to the worker(s) who can handle Vault requests for this cred store.',
+  })
+  worker_filter;
 }