RFR: 8334761: Source launcher fails with "Module reads more than one module named" error

[Christian Stein]

Please review this change to fix the setup of the optional module layer for user-supplied modules.

This fix is composed of two parts:
- modules already resolved in the boot layer are no longer part of the parent layer
- the parent layer configuration does no longer bind services

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Commit messages:
 - Add test case
 - 8334761: Source launcher fails with "Module reads more than one module named" error

Changes: https://git.openjdk.org/jdk/pull/19842/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19842&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334761
  Stats: 70 lines in 2 files changed: 66 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/19842.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19842/head:pull/19842

PR: https://git.openjdk.org/jdk/pull/19842