RFR: 8311591: Add SystemModulesPlugin test case that splits module descriptors with new local variables defined by DedupSetBuilder [v2]

[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

Christoph has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:

  8311591: Add SystemModulesPlugin test case that splits module descriptors with new local variables defined by DedupSetBuilder
  
  Co-authored-by: Oliver Kopp <kopp.dev at gmail.com>

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Changes: https://git.openjdk.org/jdk/pull/15234/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15234&range=01
  Stats: 239 lines in 9 files changed: 239 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