feat(net, driver, buf): support socket state

[abh1nav10]

This PR adds support for retrieving socket state that is whether it was empty or non-empty after the receive operation.

Closes #855

[abh1nav10]

The state of the socket(empty or non-empty) cannot directly be stored inside of Socket as all the receive methods operate on &self and Socket needs to be thread safe(both Send and Sync), therefore we cant get away with Cell. The options are to either use an AtomicBool to store the state which could turn out to be very expensive for the caller or expose identical receive methods that returns the result along with the state. If we pick the latter, I then think we could either use Option directly or introduce a public enum in compio-driver that holds the Empty NonEmpty and Unsupported state. Those identical methods would then return a tuple consisting of that enum and the result of the receive operation.
We could also modify the existing method to return that tuple but that would be a breaking change for compio-net.

I have currently added the extra methods that return a tuple consisting of an Option<bool> and the BufResult.

[George-Miao]

So...
First of all, I don't think you need to do all the heavy lifting in driver. Just use submit(op).with_extra().await will give you (BufResult<usize, T>, Extra), and you can call sock_nonempty on that. For the shared state problem, we can use synchrony::{sync,unsync}::atomic::AtomicU8 for three states (None, Some(true), Some(false)). And if sync feature is turned off, it's actually just a Cell<u8> which is very very cheap to use. Also, make the documents clear that the function will only return Some on io-uring driver, and None on all others.

Since compio-net doesn't have sync feature yet, you may want to add it first and cfg which module of synchrony (sync, unsync) to use. And add compio-net/sync to compio's sync feature as well.

[Berrysoft]

Let's add some methods to SocketState to simplify the code, maybe a pair of set & get:

fn set(&self, v: Option<bool>);
fn get(&self) -> Option<bool>;

Don't forget adding sock_nonempty for UdpSocket, TcpStream, and UnixStream.

[abh1nav10]

install-action fails on windows while running CI.

[abh1nav10]

Used the following method to avoid two conditional checks for the same thing, one while de-structuring the Result and another while having to de-structure the Option inside of SocketState::get. I am sorry if I missed something. Happy to make the change if required.

 fn set(&self, state: &compio_driver::Extra);

[George-Miao]

I'm thinking maybe we can add a sys mod under socket based on #[cfg(target_os = "linux")], which will be empty and sock_nonempty() always returns None when it's not linux, so that it imposes absolutely no overhead on other platforms.

Something like this: https://github.com/compio-rs/compio/blob/master/compio-net/src/resolve/mod.rs#L1-L9

[George-Miao]

install-action fails on windows while running CI.

Yeah windows CI is always kind of flaky. Just rerun and you're good.

[George-Miao]

LGTM. We can just merge this one if you don't feeling like implementing the sys mod. I can do that after this is merged.

[abh1nav10]

I am happy to do it. I was just reading and figuring things out.

[George-Miao]

LGTM. Thanks for the PR!