This change has the targeting pack pkgproj create an install layout based on the nupkg's data/ dir. That's picked up by the targeting pack installer project the same way it is for hostfxr and shared framework. In general, the targeting pack installer project is a copy of existing installers with very little changed.

In official builds, build the full platform manifest on win-x86, not just win-x64. Both platforms' installers need the full manifest.

The name "dotnet-targeting-pack" brings it in line with installer names like "dotnet-runtime" and "dotnet-host".

I plan to remove this script entirely, but it might as well be a little cleaner while development is ongoing.