refactor: Separate engine/p2p crate

[msgmaxim]

Pull Request

Summary

This simply moves most of the p2p module out of chainflip-engine into a separate crate. In theory this should result is slightly faster re-compilation of chainflip-engine (I measured about 1s reduction on average in a debug build). Clean compilation should also improve as engine-p2p can now be compiled in parallel to other code before chainflip-engine, and chainflip-engine is one of the biggest bottlenecks (as reported by cargo build --timings). Admittedly, the savings are small (due to p2p being a small fraction of the code), but it was an easy change to make, and if nothing else I think this change makes sense conceptually.

[codecov]

Codecov Report

❌ Patch coverage is 73.91304% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
engine/p2p/src/lib.rs	84%	3 Missing ⚠️
engine/src/p2p.rs	0%	2 Missing ⚠️
engine/src/p2p/peer_info_submitter.rs	0%	1 Missing ⚠️

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