Update to objc2 v0.6 (#4092)

* Use available! macro
* Use objc2-core-foundation and objc2-core-graphics
* Use MainThreadBound instead of StaticMainThreadBound hack

src/platform_impl/apple/appkit/util.rs

@@ -1,5 +1,8 @@
+use objc2_core_graphics::CGError;
 use tracing::trace;
 
+use crate::error::OsError;
+
 macro_rules! trace_scope {
     ($s:literal) => {
         let _crate =
@@ -26,3 +29,12 @@ impl Drop for TraceGuard {
         trace!(target = self.module_path, "Completed `{}`", self.called_from_fn);
     }
 }
+
+#[track_caller]
+pub(crate) fn cgerr(err: CGError) -> Result<(), OsError> {
+    if err == CGError::Success {
+        Ok(())
+    } else {
+        Err(os_error!(format!("CGError {err:?}")))
+    }
+}