Convert the remaining components of Shenandoah to use Atomic<T> instead of AtomicAccess, modernizing the code as has been done in other areas of Shenandoah and G1

Remaining components:
```
src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.cpp
src/hotspot/share/gc/shenandoah/shenandoahNumberSeq.cpp
src/hotspot/share/gc/shenandoah/shenandoahScanRemembered.inline.hpp
src/hotspot/share/gc/shenandoah/shenandoahHeapRegionCounters.cpp
src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.cpp
src/hotspot/share/gc/shenandoah/shenandoahController.cpp
src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.hpp
```