Port ConsoleTableApp to .NET 5.0

[vanillajonathan]

Port the ConsoleTableApp from .NET Framework 3.5 to .NET 5.0. This would make it more modern and cross-platform since .NET 5.0 is officially available and supported on Linux and Mac.

Porting should be trivial.

[minhhungit]

@vanillajonathan Thank you for your suggestion
ConsoleTableApp is just demo app, so no problem to upgrade it to .net 5, but the reason I keep it at 3.5 because we support .net framework 3.5 soI want to make sure that it works good with old frameworks
IMH upgrade to .NET 5 is not necessary