Add option for Microsoft Webview dependency

[Mino5531]

This pull request adds an option for adding the Microsoft Webview dependency to the generated msix file.
The Microsoft Webview dependency is required when using packages such as: desktop_webview_window

[9AZX]

Can be great to add this feature !

[CaptainDario]

@YehudaKremer, could you take a look at this, or maybe even a general approach to add dependencies?

[Mino5531]

Hi, just wanted to add, that I don't recommend using the dependency feature of MSIX files. The dependency installations fails pretty often and the error messages can be very confusing for users. Integrating the installation process of the Webview dependency into the flutter app directly is pretty straightforward so I would recommend doing that instead of relying on the MSIX dependency installation.

[CaptainDario]

Thank you for the heads up!
Do you have an example of how to do that?