Ladybird: Implement an AppKit chrome for macOS :^)

This adds an alternative Ladybird chrome for macOS using the AppKit
framework. Just about everything needed for normal web browsing has
been implemented. This includes:

* Tabbed, scrollable navigation
* History navigation (back, forward, reload)
* Keyboard / mouse events
* Favicons
* Context menus
* Cookies
* Dialogs (alert, confirm, prompt)
* WebDriver support

This does not include debugging tools like the JavaScript console and
inspector, nor theme support.

The Qt chrome is still used by default. To use the AppKit chrome, set
the ENABLE_QT CMake option to OFF.

Ladybird/AppKit/Utilities/Conversions.mm

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#import <Utilities/Conversions.h>
+
+namespace Ladybird {
+
+String ns_string_to_string(NSString* string)
+{
+    auto const* utf8 = [string UTF8String];
+    return MUST(String::from_utf8({ utf8, strlen(utf8) }));
+}
+
+NSString* string_to_ns_string(StringView string)
+{
+    auto* data = [NSData dataWithBytes:string.characters_without_null_termination() length:string.length()];
+    return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
+}
+
+Gfx::IntRect ns_rect_to_gfx_rect(NSRect rect)
+{
+    return {
+        static_cast<int>(rect.origin.x),
+        static_cast<int>(rect.origin.y),
+        static_cast<int>(rect.size.width),
+        static_cast<int>(rect.size.height),
+    };
+}
+
+NSRect gfx_rect_to_ns_rect(Gfx::IntRect rect)
+{
+    return NSMakeRect(
+        static_cast<CGFloat>(rect.x()),
+        static_cast<CGFloat>(rect.y()),
+        static_cast<CGFloat>(rect.width()),
+        static_cast<CGFloat>(rect.height()));
+}
+
+Gfx::IntSize ns_size_to_gfx_size(NSSize size)
+{
+    return {
+        static_cast<int>(size.width),
+        static_cast<int>(size.height),
+    };
+}
+
+NSSize gfx_size_to_ns_size(Gfx::IntSize size)
+{
+    return NSMakeSize(
+        static_cast<CGFloat>(size.width()),
+        static_cast<CGFloat>(size.height()));
+}
+
+Gfx::IntPoint ns_point_to_gfx_point(NSPoint point)
+{
+    return {
+        static_cast<int>(point.x),
+        static_cast<int>(point.y),
+    };
+}
+
+NSPoint gfx_point_to_ns_point(Gfx::IntPoint point)
+{
+    return NSMakePoint(
+        static_cast<CGFloat>(point.x()),
+        static_cast<CGFloat>(point.y()));
+}
+
+}