gbn: make logger more informative in debug level

[ViktorTigerstrom]

This PR makes the logger more informative in debug level for the gbn packet, and also way less verbose as it won't log the current resendTimeout handshakeTimeout when the values are fetched, but instead when they are set.

The logger is also updated to inform when packets are resent even under debug log level.

[ViktorTigerstrom]

For testing i recommend first modifying the debug level to debug here:

lightning-node-connect/example/index.html

Line 54 in f135fdc

'--debuglevel=trace',

.
Then make the wasm-client on master vs the new PR with make wasm, followed by the make example-server command and then create a session on the example-site in your browser and inspect the console. You'll then clearly see a difference that the new version is much more informative and less verbose :)!

[guggero]

LGTM 🎉