Reduce the makefile by adopting kpm dpa

About `kpm dpa`: https://github.com/aspnet/KRuntime/pull/1009

Stop explicitly copying assemblies from NuGet to KRE in `makefile.shade`. Instead leverage `kpm dpa` to build a KRE manifest to list files to copy.

Since this change is based on #1009, please review the last commit https://github.com/aspnet/KRuntime/commit/baefd273a1cb5f685c3720b680f302607199c192 only.

The change can't be merged until #1009 is merged.

Related Issues: #775 #779