RFR: JDK-8314211: Add NativeLibraryUnload event

Mon Aug 14 15:11:28 UTC 2023

[JDK-8313251](https://bugs.openjdk.org/browse/JDK-8313251) introduced a a NativeLibraryLoad event that provides us more detail about shared lib/dll loads.
There should be a similar event for unload operations of shared libs.

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Commit messages:
 - JDK-8314211

Changes: https://git.openjdk.org/jdk/pull/15272/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15272&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314211
  Stats: 66 lines in 7 files changed: 64 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15272.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15272/head:pull/15272

PR: https://git.openjdk.org/jdk/pull/15272