CLZ32 Support and general optimizacion

[m1kemex]

Not sure I understand this, but I think an important application of BigInts is custom bitmaps (in many implementations UInt64Array = BigInt64Array). Since JavaScript mixes floating point logic with integer logic, it'd be pretty useful to ensure unintended conversions do not destroy the contents of bitmaps, which is something an integer only type would excel at. Modern CPUs do have 64 bit CLZ instructions (_lzcnt_u64), so there is no reason not to implement a generic clz(), as hardware processes it very efficiently.

Now that many processors are switching to advanced vector instructions sets (such as AVX512, which is soon going to be standardized as a more generic AVX10), many operations with arbitrary precision math that have been traditionally very costly to implement will get a huge performance performance boost via native acceleration. I think this alone (BigInts being perceived as unacceptably slow) would significantly boost BigInt adoption.