Refactor Windows API code

[dlon]

And some other things. Main changes in this PR:

• Remove pointless locks from wireguard_nt.
• Add talpid_windows crate for generic Windows code shared between crates, mainly process snapshots and event objects.
• Replace talpid_windows_net with submodule talpid_windows::net.

Close DES-408

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This change is 

[Jontified]

Reviewed 31 of 31 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

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talpid-routing/src/windows/mod.rs line 287 at r1 (raw file):

        Ok(Some(route)) => {
            let interface_row =
                talpid_windows::net::get_ip_interface_entry(addr_family, &route.iface).map_err(

nit: can be just net

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talpid-windows/src/sync.rs line 44 at r1 (raw file):

    /// Duplicate the event object with `DuplicateHandle()`
    pub fn duplicate(&self) -> io::Result<Event> {

What is this for? Does not seem to be used anywhere.

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talpid-windows/Cargo.toml line 3 at r1 (raw file):

[package]
name = "talpid-windows"
description = "Nice abstractions for Windows"

Very* nice ;)

[Jontified]

Reviewed 5 of 5 files at r2, 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved