Added webview support for windows

[chetan-sharma-developer]

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

Chetan Sharma seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[FeodorFitsner]

Thanks for the PR!

Can you resolve conflicts and sign CLA please?

[BrentHuang]

Has webview support for desktop apps been missing?

[Muddassir-Farooq-official]

Any update

[pychans]

Wondering how this control is going...

[FeodorFitsner]

WebView user experience on Windows is different from other platforms, i.e. web view is popping up in a new window on top of Flutter app. A "proper" WebView implementation of web view for Windows is blocked by: https://github.com/flutter/flutter/issues/31713

Related Flutter issue: https://github.com/flutter/flutter/issues/37597