RFR: 8323815: Source launcher should find classes with $ in names

[Christian Stein]

Please review this fix to make the multi-file source-code launcher find classes with `$` in names, including names of packages, names of compliation units, and also names of enclosed types.

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Commit messages:
 - 8323815: Source launcher should find classes with $ in names

Changes: https://git.openjdk.org/jdk/pull/17526/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17526&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323815
  Stats: 21 lines in 2 files changed: 11 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/17526.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17526/head:pull/17526

PR: https://git.openjdk.org/jdk/pull/17526