[jdk17u-dev] RFR: 8317636: Improve heap walking API tests to verify correctness of field indexes

[Goetz Lindenmaier]

I backport this for parity with 21.0.7-oracle.

I think it is useful in 17, too.

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Commit messages:
 - Backport f31957e6a1c463e5c7041bf4eee4a1b09048e929

Changes: https://git.openjdk.org/jdk17u-dev/pull/3200/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3200&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317636
  Stats: 643 lines in 2 files changed: 643 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3200.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3200/head:pull/3200

PR: https://git.openjdk.org/jdk17u-dev/pull/3200