[feature]: docs: provide JSON examples for custom channel data

[ZZiigguurraatt]

We have some structs that can be used with json.Unmarshal to decode custom channel data (

taproot-assets/rfqmsg/custom_channel_data.go

Lines 1 to 73 in 4852be4

	package rfqmsg
	// JsonAssetBalance is a struct that represents the balance of a single asset ID
	// within a channel.
	type JsonAssetBalance struct {
	AssetID string `json:"asset_id"`
	Name string `json:"name"`
	LocalBalance uint64 `json:"local_balance"`
	RemoteBalance uint64 `json:"remote_balance"`
	}
	// JsonAssetGenesis is a struct that represents the genesis information of an
	// asset.
	type JsonAssetGenesis struct {
	GenesisPoint string `json:"genesis_point"`
	Name string `json:"name"`
	MetaHash string `json:"meta_hash"`
	AssetID string `json:"asset_id"`
	}
	// JsonAssetUtxo is a struct that represents the UTXO information of an asset
	// within a channel.
	type JsonAssetUtxo struct {
	Version int64 `json:"version"`
	AssetGenesis JsonAssetGenesis `json:"asset_genesis"`
	Amount uint64 `json:"amount"`
	ScriptKey string `json:"script_key"`
	DecimalDisplay uint8 `json:"decimal_display"`
	}
	// JsonAssetChanInfo is a struct that represents the channel information of a
	// single asset within a channel.
	type JsonAssetChanInfo struct {
	AssetInfo JsonAssetUtxo `json:"asset_utxo"`
	Capacity uint64 `json:"capacity"`
	LocalBalance uint64 `json:"local_balance"`
	RemoteBalance uint64 `json:"remote_balance"`
	}
	// JsonAssetChannel is a struct that represents the channel information of all
	// assets within a channel.
	type JsonAssetChannel struct {
	Assets []JsonAssetChanInfo `json:"assets"`
	}
	// JsonAssetChannelBalances is a struct that represents the balance information
	// of all assets within open and pending channels.
	type JsonAssetChannelBalances struct {
	OpenChannels map[string]*JsonAssetBalance `json:"open_channels"`
	PendingChannels map[string]*JsonAssetBalance `json:"pending_channels"`
	}
	// JsonCloseOutput is a struct that represents the additional co-op close output
	// information of asset channels.
	type JsonCloseOutput struct {
	BtcInternalKey string `json:"btc_internal_key"`
	AssetInternalKey string `json:"asset_internal_key"`
	ScriptKeys map[string]string `json:"script_keys"`
	}
	// JsonHtlcBalance is a struct that represents the balance of a single asset
	// HTLC.
	type JsonHtlcBalance struct {
	AssetID string `json:"asset_id"`
	Amount uint64 `json:"amount"`
	}
	// JsonHtlc is a struct that represents the asset information that can be
	// transferred via an HTLC.
	type JsonHtlc struct {
	Balances []*JsonHtlcBalance `json:"balances"`
	RfqID string `json:"rfq_id"`
	}

), however, we could really use some examples of each of these in JSON format for people to easier understand and for people who don't even use golang.

[guggero]

This is going to be refactored by #1413, see https://github.com/lightninglabs/taproot-assets/blob/0c462c10990ef7a16e1bbf76fd03f65e7d15b567/tapchannelmsg/custom_channel_data_test.go.