Allow interface names in IPv6 link-local addresses (dotnet/corefx#35278)
* Handle interface names in ipv6 addresses (link-local)
* fix test projects
* Address feedback
* Add SetLastError to if_nametoindex
* fix tests
* fix tests
* Add more tests
* move native impl to pal_networking.c/h
* add newlines to pal_networking
* fix build
* remove "Vista" comment from Interop.if_nametoindex.cs
* test fix for Uri.cs
* undo changes
* Always return 0 for if_nametoindex on UAP
Commit migrated from https://github.com/dotnet/corefx/commit/
fef0f817013ca7ebd39857b7aeecd369a9c36af5