Adjust get recovery agent method to return pending update

[gryaele]

This pull request adds support for retrieving detailed recovery binding information in the CLI and core libraries. It introduces a new command to fetch recovery binding data, expands the recovery binding data structure, and adds comprehensive tests for these changes.

CLI Enhancements:

• Added a new GetBinding command to RecoveryBindingCommand in walletkit-cli, allowing users to fetch and display recovery binding details, including recovery agent, pending recovery agent, and execution timestamp. Output is available in both human-readable and JSON formats. [1] [2] [3]

Core Library Improvements:

• Extended the RecoveryBindingResponse struct in walletkit-core to include pending_recovery_agent and execute_after fields, enabling support for pending updates and execution timing.
• Introduced a new RecoveryBinding struct and conversion logic in recovery_bindings_manager.rs to encapsulate all relevant recovery binding data, replacing the previous approach that returned only the recovery agent address. [1] [2]

Testing:

• Added tests for the new recovery binding retrieval logic, covering cases with and without pending recovery agents and execution timestamps.