Remove `SignedEnvelope::payload` in favor of
`SignedEnvelope::payload_and_signing_key`. The caller is expected to check that
the returned signing key makes sense in the payload's context.
Implement the libp2p rendezvous protocol.
> A lightweight mechanism for generalized peer discovery. It can be used for
bootstrap purposes, real time peer discovery, application specific routing, and
so on.
Co-authored-by: rishflab <rishflab@hotmail.com>
Co-authored-by: Daniel Karzel <daniel@comit.network>
