RFR: 8343227: GenShen: Fold resource mark into management of preselected regions [v2]

[William Kemper]

> `ShenandoahCollectionSetPreselector` manages a resource scoped array. It makes sense to move the `ResourceMark` into this class.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Fix builds

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Changes:
  - all: https://git.openjdk.org/shenandoah/pull/530/files
  - new: https://git.openjdk.org/shenandoah/pull/530/files/b6a136f8..c2a06a5f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=530&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=530&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah/pull/530.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/530/head:pull/530

PR: https://git.openjdk.org/shenandoah/pull/530