RFR: 8311591: Add SystemModulesPlugin test case that splits module descriptors with new local variables defined by DedupSetBuilder

[Christoph]

Add new test case with sample modules that contains some requires/exports/uses/provides.

We are just unsure if and how we should add some last step of verificaiton with the extracted and decompiled class.

Follow up task from https://github.com/openjdk/jdk/pull/14408

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Commit messages:
 - cleanup
 - rename and cleanup
 - revert back to default size of 75 for module desriptors
 - add decompilation via javap
 - extract jimage
 - add some more opens and exports
 - Merge remote-tracking branch 'origin/fix-8311591' into fix-8311591
 - Set module split size to 1
 - fix test
 - test
 - ... and 2 more: https://git.openjdk.org/jdk/compare/509f80bb...9577e7e8

Changes: https://git.openjdk.org/jdk/pull/15234/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15234&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311591
  Stats: 240 lines in 10 files changed: 240 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15234.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15234/head:pull/15234

PR: https://git.openjdk.org/jdk/pull/15234