RFR: 8346106: Verify.checkEQ: testing utility for recursive value verification

[Emanuel Peter]

In testing, we often generate "golden" values, and then compare the results with it. This requires comparison loops etc in every test. I would like to create a dedicated facility for this, to simplify testing in the future. This is also preparation for [JDK-8344942](https://bugs.openjdk.org/browse/JDK-8344942).

I have written code like this in various tests before, see:
`test/hotspot/jtreg/compiler/loopopts/superword/TestAlignVectorFuzzer.java`
`./test/hotspot/jtreg/compiler/loopopts/superword/TestMemorySegment.java`
`test/hotspot/jtreg/compiler/loopopts/superword/TestIndependentPacksWithCyclicDependency.java`.

It is now time to make a proper facility, so I can save time when writing tests in the future.

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Commit messages:
 - fix whitespaces
 - JDK-8344942

Changes: https://git.openjdk.org/jdk/pull/22715/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22715&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346106
  Stats: 834 lines in 4 files changed: 834 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22715.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22715/head:pull/22715

PR: https://git.openjdk.org/jdk/pull/22715