Closes #6851 

This PR adds an `EventEmitter` trait to the XCM Executor configuration,
enabling event emission for XCM handling. The implementation introduces
three dedicated functions to emit relevant events:

- `emit_sent_event`: Emits a `Sent` event when an XCM is successfully
sent.
- `emit_send_failure_event`: Emits a `SendFailed` event when an XCM
fails to send.
- `emit_process_failure_event`: Emits a `ProcessXcmError` event when an
XCM fails during processing.

Kusama address: FkB6QEo8VnV3oifugNj5NeVG3Mvq1zFbrUu4P5YwRoe5mQN

---------

Co-authored-by: Raymond Cheung <178801527+raymondkfcheung@users.noreply.github.com>
Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>