refactor(tvix/nix-compat): move worker_protocol into nix_daemon mod

This doesn't have much to do with the plain "wire" format, it's merely
one user of it.

Also, use the more "public" `wire::` API to read/write bytes, strings,
bools and u64s.

Change-Id: I98dddcc3004dfde7a0c009958fe84a840f77b188
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11390
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Reviewed-by: Brian Olsen <me@griff.name>

tvix/nix-compat/src/lib.rs

@@ -9,3 +9,8 @@ pub mod store_path;
 
 #[cfg(feature = "wire")]
 pub mod wire;
+
+#[cfg(feature = "wire")]
+mod nix_daemon;
+#[cfg(feature = "wire")]
+pub use nix_daemon::worker_protocol;