Add @:bridgeProperties, which creates native property bridges for all haxe properties in the annotated class

Unlike the original https://github.com/HaxeFoundation/haxe/commit/5561d13ce5ab9d8272736c8815b6bae2637b4ccb#commitcomment-6302185, this patch do not break any thing, since @:bridgeProperties always create UpperCamelCase properties, which conform to C# coding style.