RFR: 8337511: Implement JEP 404: Generational Shenandoah (Experimental) [v7]

[William Kemper]

> This PR merges JEP 404, a generational mode for the Shenandoah garbage collector. The JEP can be viewed here: https://openjdk.org/jeps/404. We would like to target JDK24 with this PR.

William Kemper has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 510 commits:

 - Merge branch 'merge-latest' into great-genshen-pr-redux
 - Use new CompactHeader forwarding APIs in generational mode
 - Merge remote-tracking branch 'jdk/master' into merge-latest
 - Merge
 - 8343649: Shenandoah: ShenandoahEvacInfo event does not follow JFR guidelines
   
   Reviewed-by: wkemper
 - Merge
 - 8343227: GenShen: Fold resource mark into management of preselected regions
   
   Reviewed-by: kdnilsen
 - Merge openjdk/jdk tip into great-genshen-pr-redux
 - Merge remote-tracking branch 'jdk/master' into merge-latest
 - Merge remote-tracking branch 'jdk/master' into merge-latest
 - ... and 500 more: https://git.openjdk.org/jdk/compare/889f9062...5e02b5d8

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Changes: https://git.openjdk.org/jdk/pull/21273/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21273&range=06
  Stats: 22977 lines in 231 files changed: 21234 ins; 886 del; 857 mod
  Patch: https://git.openjdk.org/jdk/pull/21273.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21273/head:pull/21273

PR: https://git.openjdk.org/jdk/pull/21273