TODO: Stop using pre-compiled libsodium

[joemphilips]

Currently, we use libsodium nuget package through NSec.
( since we must use ChaCha20-Poly1305 for p2p messaging)

Ideally we should compile everything in this repository, or if libsodium supports more secure deployment pipeline (e.g. deterministic building), we should incorporate that.

related: #56