Add PrunePackageReference support in project-system

[nkolev92]

Design at https://github.com/NuGet/Home/blob/dev/accepted/2024/prune-package-reference.md.

This adds support for PrunePackageReference with a Version attribute and the RestoreEnablePackagePruning property.

I know in the past we've had to do certain things to get CDK working. cc @tmeschter

Microsoft Reviewers: Open in CodeFlow

[drewnoakes]

As pointed out by @zivkan, we need a stub for the new DTB CollectPrunePackageReferences target, similar to:

project-system/src/Microsoft.VisualStudio.ProjectSystem.Managed/ProjectSystem/DesignTimeTargets/Microsoft.Managed.DesignTime.targets

Lines 424 to 428 in 5983ea9

	<!-- This target is used to collect the NuGet audit supression items. It is defined by the .NET SDK starting in version 8.0.400, but we need this no-op
	implementation when using older SDKs that don't have it; otherwise our design-time builds will fail. The NuGet.targets file in the SDK is imported
	_after_ this file, and will override this implementation with the real one (when present).
	This can (and should) be removed when we no longer need to support SDKs older than 8.0.400. -->
	<Target Name="CollectNuGetAuditSuppressions" Returns="@(NuGetAuditSuppress)" />