Update Uno version, Uno TFMs to .NET 8

[Arlodotexe]

This PR:

• Updates our Uno packages to the latest stable version
• Closes #182. Updates the TFMs that Uno runs on from net7.0 to net8.0
• Fixes any issues that arise from the move to net8.0

[Arlodotexe]

Thanks @jeromelaban for the help!

For reference, the issue was that the Uno.Wasm.Bootstrap package version doesn't align with Uno.UI/Uno.WinUI/etc. via our CommonUnoPackageVersion property and had to be updated separately. We'll need to keep this in mind for future updates. Unfortunately, we can't make use of the Uno SDK to keep things in step because it doesn't support UWP.

We should be able to close this off and include the changes in the 8.1 update.

[michael-hawker]

May want to look at the 422 equivalent as there's an Android error there:

error NETSDK1181: Error getting pack version: Pack 'Microsoft.Android.Ref.33' was not present in workload manifests. [C:\a\Windows\Windows\components\Triggers\samples\Triggers.Samples.csproj::TargetFramework=net8.0-android33.0]

[jeromelaban]

May want to look at the 422 equivalent as there's an Android error there:

This generally happens when the TargetPlatformVersion is 33 instead of 34 (which net8 targets).

[Arlodotexe]

Thanks Jerome, I'll give that a try. Found additional information on this error message here.