Support for unsigned integers

[koryphaee]

I am currently working on a project that uses a ulong as a central type in the business logic. It represents a 64bit image hash that needs to be saved in the database as well as queried via JSON API.
I am already using this cool library for my database primary keys but can't use if for the hash yet. Using long as the backing type would technically work but it doesn't feel clean.

From what I can tell it won't be a lot of work and I will try to create the PR myself. Even though I only need ulong I would add all missing unsigned types since the overhead is minimal. These would be:

StronglyType	keyword
SignedByte	sbyte
UnsignedShort	ushort
UnsignedInt	uint
UnsignedLong	ulong
NativeUnsignedInt	nuint

(taken from https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/integral-numeric-types#characteristics-of-the-integral-types)

I also need XOR support to calculate the hamming distance between two hashes but this will be a separate issue: #17

[koryphaee]

PR is done: #18