Migrate WindowsDesktop code from dotnet/core-setup to dotnet/windowsdesktop

[dagood]

Copies the code producing the Microsoft.WindowsDesktop.App shared framework from Core-Setup to the WindowsDesktop repo. For https://github.com/dotnet/core-setup/issues/5732.

Known non-blocking issues:

• Fix package validation (reference closure check) to work with nonlocal NETCoreApp #3:

  windowsdesktop/pkg/windowsdesktop/pkg/Microsoft.WindowsDesktop.App.pkgproj

  Lines 20 to 27 in 6c6432c

  	<!--
  	Turn off package validation: while in Core-Setup, this depended on extracting the list of
  	NETCoreApp DLLs from netcoreapp.depproj. We need to figure out how to implement this based on
  	a restored package, instead. (Should be somewhat simple: a target that depends on NuGet's
  	content restoration target that filters found assets based on origin package and puts them in
  	the list of ignored references.)
  	-->
  	<SkipValidatePackage>true</SkipValidatePackage>

• The [...].versions.txt file in the NuGet packages says the commit comes from core-setup #4: The Microsoft.WindowsDesktop.App.versions.txt files in the nupkgs say core-setup <commit hash>. This is defined in the sfx tooling SDK, missed it.

• Remove leftover code after the migration from the Core-Setup repo #5: Unnecessary code. There are dependencies in Version.Details.props, and Versions.props that aren't used, to start with. There are references to non-Windows platforms that aren't applicable in this repo. I removed a little of this, but there's a decent amount left.

• Code that should be shared in the shared framework tooling SDK, but isn't. This can be added over time, however there are also plans to make a good version of this SDK anyway that repos like ASP.NET Core could share. https://github.com/dotnet/core-setup/issues/4787 may track this from the Core-Setup side, but there's a possibility Create targets and tasks for authoring a shared framework arcade#2704 obviates it.

Next steps are to get the official build running, plugged into BAR, and change Core-SDK to consume this repo's outputs rather than Core-Setup. Then Core-Setup should be able to remove its WindowsDesktop build and dependencies.

I tried to split the commits up to highlight interesting changes. The last one has the change to the shared framework tooling SDK and fixes to make everything work.

/cc @jaredpar @vatsan-madhavan @zsd4yr

[dagood]

Added a couple of publish fixes from official build testing.

[MichaelSimons]

LGTM - I just have a few minor comments.

[dagood]

Good validation build, https://dev.azure.com/dnceng/internal/_build/results?buildId=375827, table:

Platform	Master
Windows (x64)	Installer (Checksum) zip (Checksum)
Windows (x86)	Installer (Checksum) zip (Checksum)

(This showed me a few issues with the actual readme link table--pushed fixes.)