Improve .NET handling in Linux environment

[SMoraisAnsys]

Currently the .NET runtime used with PyAEDT is the one provided by dotnetcore2. However there are incompatibilities with recent system libraries and we faced that issue when working with default system libraries of Ubuntu-22.04

Since we need to be compatible with such OS, I'd recommend allowing users to provide their own .NET runtime (that they install) and fallback to using dotnetcore2 if no such runtime is found. This way, current users shouldn't be impacted by any changes in pyaedt and users facing the bug I just mentionned should be able to keep working with PyAEDT.

I think we should remove dotnetcore2 from PyAEDT's dotnet install target (pyaedt[dotnet]) when reaching v1.0.