sn.exe not available on unix #7183

Binary sn.exe is not provided by .Net Core SDK 2.1.302 on unix (but it is by mono...)
IMHO dotnet/cli should be a standalone replacement for mono (when migrating to netstandard2.0/netcoreapp2.1) so needing mono to get the sn.exe binary to be able to sign seems odd to me...

My current workaround is to create a CreateSigningKey.csproj project targeting netcoreapp2.1 (since there are issue on unix with relative path Directory.GetCurrentDirectory() in netcoreapp2.0 dotnet/cli#9319 -_-) to generate the key without depending on mono (or Visual Studio)
cf: https://github.com/google/or-tools/tree/v6.8/tools/dotnet/CreateSigningKey
usage: dotnet run --project CreateSigningKey/CreateSigningKey.csproj foo.snk

Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

• ID: 4cb15371-b8d4-3fbb-db16-441f2aa47791
• Version Independent ID: c2e7c6ca-bfa4-2823-6d53-7de5f438e236
• Content: How to: Create a Public-Private Key Pair
• Content Source: docs/framework/app-domains/how-to-create-a-public-private-key-pair.md
• Product: dotnet-framework
• GitHub Login: @rpetrusha
• Microsoft Alias: ronpet

Associated WorkItem - 558442