Improved signal serialization

[willemolding]

PR summary

This changes the format of the JSON formatted signal being sent over the websocket. Prior to this the signals were debug formatted Rust which is difficult to handle in Javascript. This changes them to fully formed JSON.

This required implementing Serialize on all structs that can compose an Action and also adding the 'serde_support' feature to snowflake.

Before:

{
	"signal": {
		"Internal": "SignalZomeFunctionCall(ZomeFnCall { id: ProcessUniqueId { prefix: 7, offset: 3 }, zome_name: \"community\", cap: CapabilityRequest { cap_token: HashString(\"QmfQSbSCpjs9zctrmVueYoKRuZTxWu1sSEQmKXx5QnTACB\"), provenance: Provenance(HashString(\"HcSCJC97Yu987nhupguu3vBF3HHVtbu4m7rZpgGF7qWwiiink586Ih539kHns7r\"), Signature(\"g1Yb0AtQsiyKD/TMcxN4fOXmA2/yD08ub6kN5i2lCvKQ2NOd0V5eZKpqt4YJ9GV1fxQrM2acYcRGK0WAZEgTAw==\")) }, fn_name: \"get_community_address_by_slug\", parameters: JsonString(\"{\\\"slug\\\":\\\"hylo-holo-engineering\\\"}\") })"
	},
	"instance_id": "hylo-chat"
}

After:

{
	"signal": {
		"signal_type":"Internal",
		"action": {
			"action_type":"SignalZomeFunctionCall",
			"data":{
				"id": {"prefix":7,"offset":3},
				"zome_name":"community",
				"cap": {
					"cap_token":"QmfQSbSCpjs9zctrmVueYoKRuZTxWu1sSEQmKXx5QnTACB",
					"provenance":["HcSCJC97Yu987nhupguu3vBF3HHVtbu4m7rZpgGF7qWwiiink586Ih539kHns7r","g1Yb0AtQsiyKD/TMcxN4fOXmA2/yD08ub6kN5i2lCvKQ2NOd0V5eZKpqt4YJ9GV1fxQrM2acYcRGK0WAZEgTAw=="]
				},
			"fn_name": "get_community_address_by_slug",
			"parameters":"{\"slug\":\"hylo-holo-engineering\"}"
			}
		},
		"id":{"prefix":7,"offset":4}
	},
	"instance_id":"hylo-chat"
}

changelog

Please check one of the following, relating to the CHANGELOG

• this is a code change that effects some consumer (e.g. zome developers) of holochain core so there is an 'Unreleased' CHANGELOG item, with the format - summary of change [PR#1234](https://github.com/holochain/holochain-rust/pull/1234)
• this is not a code change, or doesn't effect anyone outside holochain core development

[maackle]

Awesome, that was easier than I imagined 😅 I added custom serialization to Signal at first because I didn't know how deep I'd have to go with derive(Serialize) for Action but it turned out not too bad.

Kind of on a related note, what do you think of #1364? Now that Internal signals are visible externally, maybe this PR is a good time to rename it to something other than Internal, like Trace?

[Connoropolous]

that rename sounds interesting @maackle
We can add it as a follow up

[zippy]

woot

[lucksus]

Great! Yeah, was looking into this as well when wrapping up @maackle PR and started adding those Serialize derivations. I stopped when I though I had to make every action and their arguments serializable as well, but seems that is not needed if you use the adjacently tagged representation?

[lucksus]

Aha!
👏 👏 👏

[maackle]

Added #1378 as a followup