Task for Nerdbank.GitVersioning and MinVer

[mzorec]

Add support for Nerdbank.GitVersioning by adding new task to FlubuCore.

https://github.com/dotnet/Nerdbank.GitVersioning

[mzorec]

I have found another .NET package for versioning https://github.com/adamralph/minver#how-it-works

https://github.com/adamralph/minver#why-not-use-gitversion-nerdbankgitversioning-or-some-other-tool

It is up for discussion which tool should FlubuCore support. We could also support both but I am not sure if that's a good idea. People might get confused which one they should use. Another options is that one of them (or both) are implemented as plugins as we already have GitVersion..