Shared single GC iteration accounting for all GCs.

Previously, each garbage collector had data that was only used
during collection. Since only one collector can be running at any
given time, we can make this data be shared between all collectors.
This reduces memory usage since we don't need to have redundant
information for each GC types. Also reduced how much code is required
to sweep spaces.

Bug: 9969166
Change-Id: I31caf0ee4d572f75e0c66863fe7db12c08ae08e7