[workerd-cxx] kj::Own refcount check and reexport (#45)

* [workerd-cxx] Export Own as kj_rs::Own and use proper refcount test

* [workerd-cxx] Use full path for isrefcounted

Author: LordGoatius

gen/src/write.rs

@@ -1664,7 +1664,7 @@ fn write_kj_own(out: &mut OutFile, key: NamedImplKey) {
     );
     writeln!(
         out,
-        "static_assert(!::std::is_base_of<::kj::Refcounted, {}>::value, \"Value must not inherit from kj::Refcounted\");",
+        "static_assert(!::kj::_::IsRefcounted<{}>, \"Value must not inherit from kj::Refcounted\");",
         inner
     );
 }

kj-rs/lib.rs

@@ -4,6 +4,7 @@ use awaiter::WakerRef;
 pub use crate::ffi::KjWaker;
 pub use awaiter::PromiseAwaiter;
 pub use future::FuturePollStatus;
+pub use own::repr::Own;
 pub use promise::KjPromise;
 pub use promise::KjPromiseNodeImpl;
 pub use promise::OwnPromiseNode;