Create window level platform specific for SetWindowSoftInputModeAdjust

[PureWeen]

Description

With XF the application and the window were the same thing so this platform specific was at the application level but with .NET MAUI we now have a concept of Window so the platform specific should be on Window

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.