[release/6.0] Add windows runtime packs as a workload (#69393)

[release/6.0] Add windows runtime packs as a workload (#69393)

Backport of https://github.com/dotnet/runtime/pull/68981

At certain points in time internally, the sdk will rev its version and insert into VS. It's at this point the sdk version will be ahead of the runtime version as we have not published anything into nuget. In MAUI and WinUI scenarios, this creates a bit of a pickle as the sdk will try to download a new version of the windows runtime pack, but it will not be available.

To get around this limitation, we are introducing a workload that will be inserted into VS where you can optionally install Windows runtime packs.

Co-authored-by: Steve Pfister <steve.pfister@microsoft.com>