RFR: 8322809: SystemModulesMap::classNames and moduleNames arrays do not match the order

[Mandy Chung]

One optimization of Jlink SystemModulesPlugin pre-resolves the module graph for modules with a main class.  It stores the name of the initial module and the generated `SystemModules` class name in two arrays that can be obtained from `SystemModulesMap::moduleNames` and `SystemModulesMap::classNames`.   The elements in the array returned by `classNames()` are supposed to correspond to the elements in the array returned by `moduleNames()`.    However, the implementation sorts both arrays by the value of the elements. 

This fix is simple and write the correct class names and not to sort the values separately.

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Commit messages:
 - minor fixes
 - 8322809: SystemModulesMap::classNames and moduleNames arrays do not match the order

Changes: https://git.openjdk.org/jdk/pull/17316/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17316&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322809
  Stats: 268 lines in 6 files changed: 261 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/17316.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17316/head:pull/17316

PR: https://git.openjdk.org/jdk/pull/17316