Implement a CoreDispatcherScheduler equivalence for Windows .NET 6

[GabrielChouinardLetourneau]

Expected Behavior

We need an implementation for net6.0-windows10.0.18362 similar to what is in MainDispatcherScheduler.UWP.cs

Actual Behavior

The MainDispatcherScheduler.Windows.cs only has similar logic (ScheduleCore) to the iOS, Android and WebAssembly files. At the moment, if we try to replicate the UWP file with the .NET 6 Windows target, we get compile errors like this: error CS0246: The type or namespace name 'CoreDispatcherScheduler' could not be found in .net-5.0 which was supposedly a known issue, since then System.Reactive hasn't been updated at all and plan on any .net-6.0 targets seem to be uncertain.

Steps to Reproduce the Problem

1. Remove the WINDOWS10_0_18362_0 condition in the top of the MainDispatcherScheduler file.
2. Copy and paste the content from MainDispatcherScheduler.UWP.cs into the Windows file.
3. Change the Windows namespace to Microsoft.
4. Inspect the remaining errors.

Specifications

• Version: 0.4.0-feature.dotnet6.51
• Platform: net6.0-windows10.0.18362
• Subsystem: