Create WindowsDesktop shared framework nupkgs and MSIs (dotnet/core-setup#5741)
* Move packaging-tools out: unwanted dir.props
Move packaging-tools from src/pkg/projects/ to src/pkg/ so the shared framework project isn't interfered with by src/pkg/projects/dir.props. Changing the dir.props would be wasted effort because packaging-tools will have to move to become shared tooling in the future.
* WindowsDesktop shared framework, nupkg + msi
Commit migrated from https://github.com/dotnet/core-setup/commit/
e1f47891f3fc715cbf73b599a5466ef8fce105ea