add support for sbyte, ushort, uint, ulong and nuint

[koryphaee]

I basically just copy-pasted the code for the existing types including tests. These commits look very similar to those adding short, byte etc. (8247470).

[koryphaee]

I had to introduct a new flag IsSigned to prevent the negation operator from being generated for unsigned types causing compiler errors.

[koryphaee]

I had to add some casts to the math operators because some types like short and byte do not yield their own type for math operators. short + short = int etc.