derive(Hash) for P2P messages

[TheBlueMatt]

In other languages (Java and C#, notably), overriding Eq without overriding Hash can lead to surprising or broken behavior. Even in Rust, its usually the case that you actually want both. Here we add missing Hash derivations for P2P messages, to at least address the first pile of warnings the C# compiler dumps.

[codecov-commenter]

Codecov Report

Attention: 55 lines in your changes are missing coverage. Please review.

Comparison is base (a025c7c) 88.82% compared to head (26c00ad) 88.96%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
lightning/src/ln/msgs.rs	1.92%	15 Missing and 36 partials ⚠️
lightning/src/util/ser.rs	0.00%	1 Missing and 1 partial ⚠️
lightning/src/onion_message/packet.rs	0.00%	0 Missing and 1 partial ⚠️
lightning/src/routing/gossip.rs	0.00%	0 Missing and 1 partial ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2716      +/-   ##
==========================================
+ Coverage   88.82%   88.96%   +0.13%     
==========================================
  Files         113      113              
  Lines       89201    91620    +2419     
  Branches    89201    91620    +2419     
==========================================
+ Hits        79235    81509    +2274     
- Misses       7727     7838     +111     
- Partials     2239     2273      +34     

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[tnull]

Ugh, still fails with

error[E0277]: the trait bound `PublicNonce: std::hash::Hash` is not satisfied
   --> lightning/src/ln/msgs.rs:333:2
    |
293 | #[derive(Clone, Debug, Hash, PartialEq, Eq)]
    |                        ---- in this derive macro expansion
...
333 |     pub next_local_nonce: Option<musig2::types::PublicNonce>,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::hash::Hash` is not implemented for `PublicNonce`
    |
    = help: the trait `std::hash::Hash` is implemented for `Option<T>`
    = note: required for `Option<PublicNonce>` to implement `std::hash::Hash`
    = note: this error originates in the derive macro `Hash` (in Nightly builds, run with -Z macro-backtrace for more info)

CI sad

[TheBlueMatt]

@arik-so can you implement Hash in your musig2 library?

[arik-so]

arik-so/rust-musig2#9

[TheBlueMatt]

Rebased after the dep bump.

[G8XSU]

LGTM! CI is failing

[TheBlueMatt]

Yea, sorry, just had to squash that fixup commit.