RFR: 8308341: JNI_GetCreatedJavaVMs returns a partially initialized JVM

[David Holmes]

We now track the in-progress and completed states of VM creation and only return a VM from JNI_GetCreatedJavaVMs when there is a fully initialized VM.

Testing: 
 - new regression test
 - tiers 1-3 (sanity)

Thanks

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Commit messages:
 - Added regression test
 - 8308341: JNI_GetCreatedJavaVMs returns a partially initialized JVM

Changes: https://git.openjdk.org/jdk/pull/14139/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14139&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308341
  Stats: 179 lines in 4 files changed: 164 ins; 2 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/14139.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14139/head:pull/14139

PR: https://git.openjdk.org/jdk/pull/14139