RFR: 8367473: Shenandoah: Make the detailed evacuation metrics a runtime diagnostic option [v2]

[William Kemper]

> Non-product builds currently have a feature to produce detailed metrics about evacuations (number of objects, number of bytes, split out by age (young, old, promotion) and thread (mutator or worker). This change makes this feature accessible in release builds as a diagnostic option.

William Kemper has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge remote-tracking branch 'jdk/master' into make-evac-tracking-runtime-option
 - Only print evacuation info when evac tracking is enabled (generational mode fix)
 - Make detailed evacuation tracking a diagnostic option in product builds

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27238/files
  - new: https://git.openjdk.org/jdk/pull/27238/files/013480d2..bbee4ee3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27238&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27238&range=00-01

  Stats: 12926 lines in 600 files changed: 6899 ins; 2751 del; 3276 mod
  Patch: https://git.openjdk.org/jdk/pull/27238.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27238/head:pull/27238

PR: https://git.openjdk.org/jdk/pull/27238