Add Infra for porting lib only packages to use dotnet pack instead of pkgprojs (#51765)
* add infra and move projects to use dotnet pack
* adddress feedback
* address feedback
* donot include buildoutput from netfx during sourcebuild
* some more feedback points
* add SuppressDependenciesWhenPacking as well
* Apply suggestions from code review
Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>
* Update src/libraries/Directory.Build.targets
Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>
* remove warn
* Update src/libraries/Directory.Build.targets
Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>
* donot set includebuild output in outerbuild
Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>