Implement IAM propagation to S3 servers (#8130)

* Implement IAM propagation to S3 servers

- Add PropagatingCredentialStore to propagate IAM changes to S3 servers via gRPC
- Add Policy management RPCs to S3 proto and S3ApiServer
- Update CredentialManager to use PropagatingCredentialStore when MasterClient is available
- Wire FilerServer to enable propagation

* Implement parallel IAM propagation and fix S3 cluster registration

- Parallelized IAM change propagation with 10s timeout.
- Refined context usage in PropagatingCredentialStore.
- Added S3Type support to cluster node management.
- Enabled S3 servers to register with gRPC address to the master.
- Ensured IAM configuration reload after policy updates via gRPC.

* Optimize IAM propagation with direct in-memory cache updates

* Secure IAM propagation: Use metadata to skip persistence only on propagation

* pb: refactor IAM and S3 services for unidirectional IAM propagation

- Move SeaweedS3IamCache service from iam.proto to s3.proto.
- Remove legacy IAM management RPCs and empty SeaweedS3 service from s3.proto.
- Enforce that S3 servers only use the synchronization interface.

* pb: regenerate Go code for IAM and S3 services

Updated generated code following the proto refactoring of IAM synchronization services.

* s3api: implement read-only mode for Embedded IAM API

- Add readOnly flag to EmbeddedIamApi to reject write operations via HTTP.
- Enable read-only mode by default in S3ApiServer.
- Handle AccessDenied error in writeIamErrorResponse.
- Embed SeaweedS3IamCacheServer in S3ApiServer.

* credential: refactor PropagatingCredentialStore for unidirectional IAM flow

- Update to use s3_pb.SeaweedS3IamCacheClient for propagation to S3 servers.
- Propagate full Identity object via PutIdentity for consistency.
- Remove redundant propagation of specific user/account/policy management RPCs.
- Add timeout context for propagation calls.

* s3api: implement SeaweedS3IamCacheServer for unidirectional sync

- Update S3ApiServer to implement the cache synchronization gRPC interface.
- Methods (PutIdentity, RemoveIdentity, etc.) now perform direct in-memory cache updates.
- Register SeaweedS3IamCacheServer in command/s3.go.
- Remove registration for the legacy and now empty SeaweedS3 service.

* s3api: update tests for read-only IAM and propagation

- Added TestEmbeddedIamReadOnly to verify rejection of write operations in read-only mode.
- Update test setup to pass readOnly=false to NewEmbeddedIamApi in routing tests.
- Updated EmbeddedIamApiForTest helper with read-only checks matching production behavior.

* s3api: add back temporary debug logs for IAM updates

Log IAM updates received via:
- gRPC propagation (PutIdentity, PutPolicy, etc.)
- Metadata configuration reloads (LoadS3ApiConfigurationFromCredentialManager)
- Core identity management (UpsertIdentity, RemoveIdentity)

* IAM: finalize propagation fix with reduced logging and clarified architecture

* Allow configuring IAM read-only mode for S3 server integration tests

* s3api: add defensive validation to UpsertIdentity

* s3api: fix log message to reference correct IAM read-only flag

* test/s3/iam: ensure WaitForS3Service checks for IAM write permissions

* test: enable writable IAM in Makefile for integration tests

* IAM: add GetPolicy/ListPolicies RPCs to s3.proto

* S3: add GetBucketPolicy and ListBucketPolicies helpers

* S3: support storing generic IAM policies in IdentityAccessManagement

* S3: implement IAM policy RPCs using IdentityAccessManagement

* IAM: fix stale user identity on rename propagation

weed/credential/credential_manager.go

@@ -8,6 +8,8 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/pb/iam_pb"
 	"github.com/seaweedfs/seaweedfs/weed/s3api/policy_engine"
 	"github.com/seaweedfs/seaweedfs/weed/util"
+	"github.com/seaweedfs/seaweedfs/weed/wdclient"
+	"google.golang.org/grpc"
 )
 
 // CredentialManager manages user credentials using a configurable store
@@ -42,6 +44,11 @@ func NewCredentialManager(storeName CredentialStoreTypeName, configuration util.
 	}, nil
 }
 
+// SetMasterClient sets the master client to enable propagation of changes to S3 servers
+func (cm *CredentialManager) SetMasterClient(masterClient *wdclient.MasterClient, grpcDialOption grpc.DialOption) {
+	cm.store = NewPropagatingCredentialStore(cm.store, masterClient, grpcDialOption)
+}
+
 // GetStore returns the underlying credential store
 func (cm *CredentialManager) GetStore() CredentialStore {
 	return cm.store