Command hex format

[Lagrang3]

Added json outputs to gl-cli commands.

For example:

$ glcli --json node getinfo
{
  "address": [],
  "alias": "...",
  "binding": [],
  "blockheight": 949533,
  "color": "...",
  "fees_collected_msat": 0,
  "id": "...",
  "lightning_dir": "/tmp/bitcoin",
  "network": "bitcoin",
  "num_active_channels": 0,
  "num_inactive_channels": 0,
  "num_peers": 1,
  "num_pending_channels": 0,
  "our_features": {
    "channel": "",
    "init": "0898880a8a59a1",
    "invoice": "02000002024100",
    "node": "8898880a8a59a1"
  },
  "version": "v25.12gl1"
}

I did this by hand, for every possible gRPC response that we use, which are not all of CLN's commands.
I know this is flawed, since we have no guarantee of correctedness by developer error or API changes and
as the number of gRPC commands grow this task becomes tedious.
But right now it is manageable and until we find a trick to make it automatic we can use this.

[cdecker]

Very good idea, the JSON output is likely more useful than the native protobuf serialization. However, I know that there are ways to add attributes to the structs that are generated in Rust. The App team had used it a while ago to convert arbitrary messages to JSON for their own logging.

They were using the message_attribute() builder call to have the generated messages automatically be annotated with #[derive(Serialize, Deserialize)] and then did something to convert binary fields to hex, I think with a custom serializer that knew how to identify and handle the binary values. This would solve the manual maintenance you mention above and absolutely ensure that the JSON and binary representation remain in sync.

[cdecker]

Let me know if you'd like to merge this as is, so the functionality is available, or whether you want to look into a more complex, but simpler longer term, solution :-)