feature: Add a MAUI app to samples

[worldbeater]

Is your feature request related to a problem? Please describe.

Xamarin.Forms will ship a new major version later this year, and continue to ship minor and service releases every 6 weeks through .NET 6 GA in November 2021. The final release of Xamarin.Forms will be serviced for a year after shipping, and all modern work will shift to .NET MAUI. — https://devblogs.microsoft.com/dotnet/introducing-net-multi-platform-app-ui/

Since Xamarin.Forms is going to be replaced by MAUI, probably worth creating a sample app that demonstrates how to use MAUI with ReactiveUI.Validation. Preferably the new app targeting MAUI should live inside https://github.com/reactiveui/ReactiveUI.Validation/tree/main/samples and reuse the view models from LoginApp as Avalonia, UWP, WPF and Windows Forms sample apps do.

[glennawatson]

Maui isn't out yet so xamarin isn't deprecated

[worldbeater]

Ah thanks! .NET MAUI GA has been postponed to Q2 2022 https://github.com/dotnet/maui/wiki/Roadmap dotnet workload doesn't include Xamarin so I thought for some reason that MAUI has been already released. Updated the issue.

GitHub

Roadmap · dotnet/maui Wiki

.NET MAUI is the .NET Multi-platform App UI, a framework for building native device applications spanning mobile, tablet, and desktop. - Roadmap · dotnet/maui Wiki