Add uint calculation

[dunds-com]

When having an unsigned integer in the model, it didn't allow calculations.

var template = Template.Parse("{{ test1 * test2 }}");
var result = template.Render(new
{
	test1 = (uint)55,
	test2 = (uint)80
});

Console.WriteLine(result);
Console.ReadKey(true);

Unsupported types 55/uint * 80/uint for binary operation

This PR adds support for uints.

[xoofx]

Could you add a unit test?

[dunds-com]

Should I add a scriban file as a unit test?

[xoofx]

Should I add a scriban file as a unit test?

Oh, no, you can add just a test in e.g. TestRuntime.cs similar to what is already done for some other specific cases.

Wondering also if the result should not be ulong in the end. BigInteger is quickly quite less practical.