font: look up Apple Color Emoji by exact name on macOS

The Apple Color Emoji fallback font was discovered with the generic
discovery path, which builds a CTFontCollection and runs system-wide
font matching. Since we know the exact font we want, we can look it
up directly with CTFontCreateWithName instead.

pkg/macos/text/font.zig

@@ -18,6 +18,17 @@ pub const Font = opaque {
         ) orelse Allocator.Error.OutOfMemory;
     }
 
+    pub fn createWithName(name: *foundation.String, size: f32) Allocator.Error!*Font {
+        return @as(
+            ?*Font,
+            @ptrFromInt(@intFromPtr(c.CTFontCreateWithName(
+                @ptrCast(name),
+                size,
+                null,
+            ))),
+        ) orelse Allocator.Error.OutOfMemory;
+    }
+
     pub fn createForString(
         self: *Font,
         str: *foundation.String,