platform: Update metadata for export platforms

Updates the logos of for macOS, Android, and iOS; Also
changes "Mac OSX" to "macOS"

Addresses https://github.com/godotengine/godot-proposals/issues/1161

platform/osx/export/export.cpp

@@ -95,8 +95,8 @@ protected:
 	virtual void get_export_options(List<ExportOption> *r_options) override;
 
 public:
-	virtual String get_name() const override { return "Mac OSX"; }
-	virtual String get_os_name() const override { return "OSX"; }
+	virtual String get_name() const override { return "macOS"; }
+	virtual String get_os_name() const override { return "macOS"; }
 	virtual Ref<Texture2D> get_logo() const override { return logo; }
 
 	virtual List<String> get_binary_extensions(const Ref<EditorExportPreset> &p_preset) const override {