feat: add shadow network simulator support

[turuslan]

What was wrong?

Couldn't run ream in shadow network simulator.
Shadow doesn't implement some setsockopt options.

How was it fixed?

Patch quinn-udp to avoid unsupported setsockopt by using fallback.rs instead of unix.rs.

quinn-udp is transitive dependency
ream -> libp2p -> libp2p-quic -> quinn -> quinn-udp
so feature = "shadow" was added to every crate in that chain.

To-Do

• I have read CONTRIBUTING.md.
• This PR title follows conventional commits.

[syjn99]

I think we can figure out a better way, not patching the full libp2p with forked one. Also it seems we only need to patch quinn-udp but it's a transitive dep so I should check.

@KolbyML Is it possible to patch only when a specific rust flag is enabled? For example in this case, --feature shadow.

[KolbyML]

I am not a fan of adding unmaintained dependencies to our Cargo.toml

Regardless if we were to do something like this we would instead

diff --git a/.cargo/config-shadow.toml b/.cargo/config-shadow.toml
new file mode 100644
index 0000000..cb8b6ca
--- /dev/null
+++ b/.cargo/config-shadow.toml
@@ -0,0 +1,7 @@
+[patch.crates-io]
+# https://github.com/shadow/shadow
+libp2p = { git = "https://github.com/qdrvm/rust-libp2p.git", branch = "feature/shadow-0.55.0" }
+libp2p-mplex = { git = "https://github.com/qdrvm/rust-libp2p.git", branch = "feature/shadow-0.55.0" }
+libp2p-quic = { git = "https://github.com/qdrvm/rust-libp2p.git", branch = "feature/shadow-0.55.0" }
+quinn = { git = "https://github.com/qdrvm/quinn.git", branch = "feature/shadow-0.5.11" }
+quinn-udp = { git = "https://github.com/qdrvm/quinn.git", branch = "feature/shadow-0.5.11" }

and build Ream with cargo build --config .cargo/config-shadow.toml to include these patches.

But since we will be upgrading to libp2p version 0.56 shortly, I don't think we should merge this.

Even then once version 0.57 came out it would break again. I don't want to maintain this so it would probably be removed later.

So maybe it would be best to keep this on your local testing branch of ream?

[KolbyML]

I don't think we should downgrade our packages