RFR: 8271242: Add Arena regression tests

[Thomas Stuefe]

May I please have reviews for these test additions. These are new regression tests for hotspot arenas. We don't have any and it makes sense to have them since this code is fragile and we work on it.

It also contains some new gtest utility functions which I will use to consolidate some more test coding, mainly in the metaspace gtests (in a future rfe).

It also comes with a new jtreg gtest launcher for arena tests to test UseMallocOnly mode. As long as we support that, we should test it.

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tests: 
- gtests, manually with 32/64 bit and with/without UseMallocOnly
- GHAs

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Commit messages:
 - start

Changes: https://git.openjdk.java.net/jdk/pull/4909/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4909&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271242
  Stats: 465 lines in 4 files changed: 465 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4909.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4909/head:pull/4909

PR: https://git.openjdk.java.net/jdk/pull/4909