libp2p
protocols/noise: Inline `handshake` functions into upgrade traits
Description
This fell out of https://github.com/libp2p/rust-libp2p/pull/2903. It removes a layer of indirection by inlining the various handshake functions into the respective upgrade traits. This should hopefully make it clearer, what message exchange actually happens for a particular handshake pattern.
This also removes a bit of complexity in terms of what the {send,receive}_identity functions do as several parts of it were conditional based on actually statically known state.
This is a breaking change because we make the entire handshake module private and thus prevent external users from re-using our handshake functions. However, I don't think having these public in the first place was a good move. The libp2p-noise crate specifically offers support for noise within libp2p and should not be used for noise handshakes in general.
Conveniently, this is also a net-negative in terms of code size :)
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Open Questions
Change checklist
- [x] I have performed a self-review of my own code
- [x] I have made corresponding changes to the documentation
- ~[ ] I have added tests that prove my fix is effective or that my feature works~
- [x] A changelog entry has been made in the appropriate crates
