Add support for ceph-mgr-dump

[shutstart]

Add support for ceph mgr dump command

Description

We need to implement support for the ceph mgr dump command in our API to enable retrieval of manager information from Ceph clusters.

Technical Requirements

1. Create a new RPC service method:

   rpc GetCephMgrDump(google.protobuf.Empty) returns (google.protobuf.Struct)

2. The method should:

   • Use our existing Ceph connection method to execute the mgr dump command
   • Return the JSON output as a google.protobuf.Struct without modification

Implementation Details

• Implement the handler in /pkg/api/status_api_handlers.go following the existing patterns
• Follow the implementation approach used for other status commands
• Properly parse the JSON response before returning

Acceptance Criteria

• ✅ Service method implementation is complete and functional
• ✅ Method correctly returns the JSON data from mgr dump as a Protobuf Struct
• ✅ Comprehensive integration tests are written following the pattern in test/status_test.go
• ✅ Error handling for command failures is implemented

Related Resources

• Existing API handlers
• Status test for reference