[14] RFR (S) 8240749: Shenandoah: refactor ShenandoahUtils

[Roman Kennke]

Looks good, thanks!

Roman


> Original change:
>   https://bugs.openjdk.java.net/browse/JDK-8240749
>   https://hg.openjdk.java.net/jdk/jdk/rev/a74b7501917d
> 
> It has a minor conflict due to missing JDK-8228818, so hunk in shenandoahHeap.cpp does not have
> associated phase_timings changes. I moved the ShenandoahGCPhase to the same place, though.
> 
> 14u webrev:
>   https://cr.openjdk.java.net/~shade/8240749/webrev.14u.01/
> 
> Testing: hotspot_gc_shenandoah
>