RFR (S) 8244732: Shenandoah: move heuristics code to gc/shenandoah/heuristics

[Aleksey Shipilev]

RFE:
  https://bugs.openjdk.java.net/browse/JDK-8244732

For cleanliness reasons, it makes sense to move all related heuristics code to
gc/shenandoah/heuristics subfolder. This mostly affects the move of shenandoahHeuristics.hpp itself.

Webrev:
  https://cr.openjdk.java.net/~shade/8244732/webrev.01/

Testing: hotspot_gc_shenandoah

-- 
Thanks,
-Aleksey