refactor(io): Refactor network types into net::io modules, add runtime fallback for-uring

[XAMPPRocky]

This PR fixes #1183 by refactoring the network listening code to allow for falling all the way back to epoll on Linux at runtime.

As part of that I've consolidated all our different IO backends into a single net::io module, and then I made a module for each of our different kinds of backends (polling, completion, NIC) and moved platform specific code there, that way more of the code can be compiled on macOS and Windows which makes development easier with more of the logic being shared.

This should be a bit tidier with #1185 but I wanted to fix #1183 first.

[Jake-Shadle]

IMO it's a bit suspect to fallback to epoll by default if io-uring is unavailable due to potential performance loss that the user won't be made aware of.

[XAMPPRocky]

due to potential performance loss that the user won't be made aware of.

They will be aware because we log an error when io-uring fails, so they see that it failed.

[quilkin-bot]

Build Failed 😭

Build Id: f122d74e-f3e1-492f-a3f4-d1bbd4059ceb

Status: FAILURE

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