auto probing win7, win81 and win10 rids + osx10.10,osx10.11, osx10.12, osx10.13, osx10.14, osx10.15

The structure of the runtime folder, for platform specific dll's is more comprehensive than the current probing logic implemented in the native assembly resolver.

Updated rid list:
https://github.com/dotnet/runtime/blob/master/src/libraries/pkg/Microsoft.NETCore.Platforms/runtime.json