Remove 'IsWpfTempProject' workaround after .NET Core Preview 8 is released

[ryalanms]

WPF for .NET Core is adding PackageReference restore to temporary project compilation in Preview 8. When Preview 8 is released, the existing workaround needs to be removed from Arcade.

https://github.com/dotnet/arcade/blob/master/src/Microsoft.DotNet.Arcade.Sdk/tools/Workarounds.props#L5
https://github.com/dotnet/arcade/blob/master/src/Microsoft.DotNet.Arcade.Sdk/tools/Workarounds.targets#L26

[vatsan-madhavan]

We should have a tracking issue in wpf repo as well so it gets triaged and prioritized for P8.

[ryalanms]

@vatsan-madhavan: I've opened issue dotnet/wpf#1055 in the WPF repo. Thanks.

[tmat]

We can't remove the workaround since we are not using Core WPF in most repos, but .NET Framework WPF. We can condition the workaround on TFM though.

[vatsan-madhavan]

Makes sense. In the next PR, use condition to detect WindowsDesktop Sdk (see dotnet/wpf#1027 - there is a property you can sniff).

[markwilkie]

Seems this is resolved. Pls reopen if not.