Add Comparable to UInt64

[obriensystems]

as part of #10
fix

results.stream().sorted().forEach(x -> System.out.println(x)); 

Exception in thread "main" java.lang.ClassCastException: class dev.obrienlabs.performance.nbi.math.ULong128Impl cannot be cast to class java.lang.Comparable (dev.obrienlabs.performance.nbi.math.ULong128Impl is in unnamed module of loader 'app'; java.lang.Comparable is in module java.base of loader 'bootstrap')