Use different path to NETCore SDK

[FilipToth]

BUG REPORT

As of now (not sure if it's committed as I've been working on a huge update on my local branch), we're using a preset path to the dotnet SDK, this should be changed immediately to something more dynamic where simply installing a new dotnet SDK will break the whole REPL system.

Problem

at Alto.AltoRepl::CreateBaseConfig(string)

 var baseConfig = new Dictionary<string, string>
{
    {"NETCorePath", "C:/Program Files/dotnet/packs/Microsoft.NETCore.App.Ref/6.0.0-preview.7.21377.19/"}
};