op-mode: T6746: add CLI options to show/monitor log of vyos-configd

This is pretty usefull to monitor what's going on under the hood

Dec 08 15:27:34 vyos-configd[4324]: Received message: {"type": "init"}
Dec 08 15:27:34 vyos-configd[4324]: config session pid is 4400
Dec 08 15:27:34 vyos-configd[4324]: config session sudo_user is cpo
Dec 08 15:27:34 vyos-configd[4324]: commit_scripts: ['protocols_babel', 'protocols_bfd', 'protocols_bgp']
Dec 08 15:27:34 vyos-configd[4324]: Received message: {"type": "node", "last": false, "data": "/usr/libexec/vyos/conf_mode/protocols_babel.py"}
Dec 08 15:27:34 vyos-configd[4324]: Sending reply: error_code 1 with output
Dec 08 15:27:34 vyos-configd[4324]: Received message: {"type": "node", "last": false, "data": "/usr/libexec/vyos/conf_mode/protocols_bgp.py"}
Dec 08 15:27:34 vyos-configd[4324]: Sending reply: error_code 1 with output
Dec 08 15:27:34 vyos-configd[4324]: Received message: {"type": "node", "last": true, "data": "/usr/libexec/vyos/conf_mode/protocols_bfd.py"}
Dec 08 15:27:34 vyos-configd[4324]: Sending reply: error_code 1 with output
Dec 08 15:27:34 vyos-configd[4324]: scripts_called: ['protocols_babel', 'protocols_bgp', 'protocols_bfd']
Dec 08 15:27:34 vyos-configd[4324]: FRR: Reloading configuration - tries: 1 Python class ID: 139842739583248

Debugging the new FRRender/vyos-config integration