Add temporary mac_wgpu platform for hacking up testing wgpu on macOS

crates/gpui/src/platform/mac_wgpu/window_appearance.rs

@@ -0,0 +1,35 @@
+use crate::WindowAppearance;
+use cocoa::{
+    appkit::{NSAppearanceNameVibrantDark, NSAppearanceNameVibrantLight},
+    base::id,
+    foundation::NSString,
+};
+use objc::{msg_send, sel, sel_impl};
+use std::ffi::CStr;
+
+impl WindowAppearance {
+    pub(crate) unsafe fn from_native(appearance: id) -> Self {
+        let name: id = msg_send![appearance, name];
+        if name == NSAppearanceNameVibrantLight {
+            Self::VibrantLight
+        } else if name == NSAppearanceNameVibrantDark {
+            Self::VibrantDark
+        } else if name == NSAppearanceNameAqua {
+            Self::Light
+        } else if name == NSAppearanceNameDarkAqua {
+            Self::Dark
+        } else {
+            println!(
+                "unknown appearance: {:?}",
+                CStr::from_ptr(name.UTF8String())
+            );
+            Self::Light
+        }
+    }
+}
+
+#[link(name = "AppKit", kind = "framework")]
+extern "C" {
+    pub static NSAppearanceNameAqua: id;
+    pub static NSAppearanceNameDarkAqua: id;
+}