We don't follow the JSON-RPC spec when closing a channel

[aatifsyed]

forest/src/rpc/channel.rs

Line 318 in 42964f8

let resp = close_channel_response(channel_id);

The response should contain the id of the request, but ours in unconditionally null

[aatifsyed]

cc @elmattic

[elmattic]

We definitely have an issue when sending the closing response (after getting the channel cancel payload from the client).

Lotus closing message:
{"jsonrpc":"2.0","method":"xrpc.ch.close","params":[<channel_id>]}

Forest closing message:
{"jsonrpc":"2.0","result":{"jsonrpc":"2.0","method":"xrpc.ch.close","params":[<channel_id>]},"id":null}

I don't think it really matters to set ID to something in this context.