[SPARK-3250] Implement Gap Sampling optimization for random sampling

More efficient sampling, based on Gap Sampling optimization:
http://erikerlandson.github.io/blog/2014/09/11/faster-random-samples-with-gap-sampling/

I believe `Math.log1p(-f)` will be slightly more accurate for very small `f`, and I suppose `f` could be quite small in some use cases.