Rename this tool to dotnet-uninstall

[cr3wdayt5p]

The "Core" branding is long gone from the .NET ecosystem. No supported versions of .NET use "Core" anymore (see https://dotnet.microsoft.com/en-us/download/dotnet).

I think it is time to drop the core part of the name of this tool.

This very minor change would make the .NET ecosystem slightly more user friendly to newcomers, i.e. only 2 CLI tools are needed (dotnet and dotnet-uninstall) – and they have similar names.