Custom title bars (window control overlays) #4029

Custom titlebars are not natively supported on Windows (WebView2) which means wails can't support them currently, but there is actually an issue in WebView2Feedback that resulted in a specification, and they are working on adding support for window control overlays. Until then, the only solution is to mock them in HTML CSS (or any other frontend framework). I will eventually provide a base for mocking them in react.js + tailwindcss, so that anyone can do them quickly (they are quite convincing). Example: