Diamond in Csharp

[HulinCedric]

Here is a Csharp version (targeting dotnet 6) of the diamond kata.

• For approaches description, the Java documentation has been adapted to Csharp one.
• For the incremental approach, I have taken test steps inspiration from Sandro Mancuso repository.
• For the iterative approach, I have taken test steps from Seb Rose original blog post.

Let me know if there is something to improve or to adapt in order to be consistent with other languages skeleton.