Add support for customizing EnvironmentOptions - specifically AdditionalBrowserArguments

[changchaishi]

Hi I notice in pkg\edge\chromium.go, that the package straight up use a 0 pointer for creating WebView2EnvironmentWithOptions, is there a way or guide to show how to set something like this?

[jchv]

There's definitely tons of things that could be implemented with some effort, mainly just around wrapping more COM objects and plumbing them as needed. I'm still happy to review/accept pull requests but the main reason I haven't made many improvements is that I don't really have any native Windows setups anymore, and don't work too much on Windows stuff at the moment.