Windows desktop support [can provide implementation]

## Use case

Flutter has support for desktop embedders in various different stages of preview on different desktop platforms. As part of a recent hackathon, myself and a couple of folks built a proof of concept webview specifically for pop-up / authentication scenarios here:

https://github.com/clarkezone/flutter_win_webview

We were able to successfully use this implementation with https://pub.dev/packages/flutter_aad_oauth (which depends on flutter_webview_plugin) to successfully get Microsoft Graph Oauth scenarios working on Windows by merely supporting the method channel. Our implementation is using the new Webview2 control powered by Edge chromium.

## Proposal

We are considering contributing the Windows implementation to this project. There is more work to do to get parity with what you have already in flutter_webview_plugin for other platforms (notably secure credential local storage and javascript support). Before embarking on the work to fill the gaps, fork, integrate and prepare a PR we wanted to check if you'd be open to accepting it?