[Feature request] C# should use a maintained script runner by default

**Is your feature request related to a problem? Please describe.**
The current C# script runnier is `scriptcs` which is no longer maintained. See [this announcement](https://github.com/scriptcs/scriptcs/issues/1323#issue-1392082445) for more details.

**Describe the solution you'd like**
Code Runner should specify a maintained script runner by default such as [dotnet script](https://github.com/dotnet-script/dotnet-script).