Refactor RPC and network events

[austinabell]

Summary of changes
Changes introduced in this pull request:

• Replaces RPC module with new RequestResponse module in libp2p. Was just going to refactor, but I think this is a better long term solution
  • wasn't usable as is, which is why the fork, but there isn't anything unreasonable in my PR I don't think, so will circle back to switch back to a release if/when that happens
• Updates the events emitted from the network service and the interface in slightly

Reference issue to close (if applicable)

Closes #505

Other information and links

[ec2]

What do you think of getting rid of RPCEvent? Doesn't make sense to put em together IMO if the Hello and BS behaviours are separated. Doesn't seem to make sense to treat them as variants of some RPCEvent enum as they're handled and used completely differently in most parts of Forest

[austinabell]

What do you think of getting rid of RPCEvent? Doesn't make sense to put em together IMO if the Hello and BS behaviours are separated. Doesn't seem to make sense to treat them as variants of some RPCEvent enum as they're handled and used completely differently in most parts of Forest

Idk I don't have a strong opinion but it seemed way less clean with duplication and unnecessary conversions. I might just update anyway though because I guess the interface from outside the service is better not to have to wrap the RPC variant.

I'll just commit and can always just pull it off again. Seemed more usable way it was, but it's fine by me to have it this way