* iam: add XML responses for managed user policy APIs
* s3api: implement attach/detach/list attached user policies
* s3api: add embedded IAM tests for managed user policies
* iam: update CredentialStore interface and Manager for managed policies
Updated the `CredentialStore` interface to include `AttachUserPolicy`,
`DetachUserPolicy`, and `ListAttachedUserPolicies` methods.
The `CredentialManager` was updated to delegate these calls to the store.
Added common error variables for policy management.
* iam: implement managed policy methods in MemoryStore
Implemented `AttachUserPolicy`, `DetachUserPolicy`, and
`ListAttachedUserPolicies` in the MemoryStore.
Also ensured deep copying of identities includes PolicyNames.
* iam: implement managed policy methods in PostgresStore
Modified Postgres schema to include `policy_names` JSONB column in `users`.
Implemented `AttachUserPolicy`, `DetachUserPolicy`, and `ListAttachedUserPolicies`.
Updated user CRUD operations to handle policy names persistence.
* iam: implement managed policy methods in remaining stores
Implemented user policy management in:
- `FilerEtcStore` (partial implementation)
- `IamGrpcStore` (delegated via GetUser/UpdateUser)
- `PropagatingCredentialStore` (to broadcast updates)
Ensures cluster-wide consistency for policy attachments.
* s3api: refactor EmbeddedIamApi to use managed policy APIs
- Refactored `AttachUserPolicy`, `DetachUserPolicy`, and `ListAttachedUserPolicies`
to use `e.credentialManager` directly.
- Fixed a critical error suppression bug in `ExecuteAction` that always
returned success even on failure.
- Implemented robust error matching using string comparison fallbacks.
- Improved consistency by reloading configuration after policy changes.
* s3api: update and refine IAM integration tests
- Updated tests to use a real `MemoryStore`-backed `CredentialManager`.
- Refined test configuration synchronization using `sync.Once` and
manual deep-copying to prevent state corruption.
- Improved `extractEmbeddedIamErrorCodeAndMessage` to handle more XML
formats robustly.
- Adjusted test expectations to match current AWS IAM behavior.
* fix compilation
* visibility
* ensure 10 policies
* reload
* add integration tests
* Guard raft command registration
* Allow IAM actions in policy tests
* Validate gRPC policy attachments
* Revert Validate gRPC policy attachments
* Tighten gRPC policy attach/detach
* Improve IAM managed policy handling
* Improve managed policy filters
