Sim2h space data remote debugging

[lucksus]

PR summary

Adds a WireMessge::Debug and WireMessage::DebugResponse(BTreeMap<SpaceHash, String>) to retrieve all space data as JSON serialized string.

hc can request this debug state dump and write it to file(s) (each space data into a separate one):

[nix-shell:~/hc]$ hc sim2h-client --message debug --url ws://localhost:9000
url: ws://localhost:9000
message: debug
connecting to: ws://127.0.0.1:9000/
Generated agent id: HcSCiDdSTjGaajts3zqY9WqC4zfJhnuhs8m4R6rC35RwObu8Uc6seVaYWe9eija
Await successfull
Sending wire message to sim2h: Debug
Ack(3079098903191232539)
Got DebugResponse for 1 spaces.
Writing Sim2h state dump for space QmXghcjdFQ7vEvihuBVQdiQBATGnRo6qX5wNxrq6HdNH9i to file: QmXghcjdFQ7vEvihuBVQdiQBATGnRo6qX5wNxrq6HdNH9i.json

testing/benchmarking notes

( if any manual testing or benchmarking was/should be done, add notes and/or screenshots here )

followups

Make this optional (per command line parameter / configuration) such that public sim2h servers don't offer potential sensitive information to everybody

changelog

• if this is a code change that effects some consumer (e.g. zome developers) of holochain core, then it has been added to our between-release changelog with the format

- summary of change [PR#1234](https://github.com/holochain/holochain-rust/pull/1234)

documentation

• this code has been documented according to our docs checklist

[zippy]

I think this is going to need dumping just the response to a file maybe JSON encoded to be usefull?

[lucksus]

I think this is going to need dumping just the response to a file maybe JSON encoded to be usefull?

Yep, mainly why I left this as WIP. The current plain debug output is hard to read..

[zippy]

Fails if message debug data is bigger than max tungstenite message size!

[zippy]

WOOT!