RFR: 8353267: jmod create finds the wrong set of packages when class file are in non-package location

[Alan Bateman]

`jmod create` maps the contents of the module to a set of packages. This mapping derives illegal package names when class resources are located in non-package locations, e.g. in the META-INF tree. `jlink` also has an issue in this area and doesn't correctly determine if a resource is in a named package when the resource is class file in a non-package location.

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Commit messages:
 - Remove trailing space
 - Improve comment
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/24362/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24362&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8353267
  Stats: 214 lines in 4 files changed: 180 ins; 6 del; 28 mod
  Patch: https://git.openjdk.org/jdk/pull/24362.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24362/head:pull/24362

PR: https://git.openjdk.org/jdk/pull/24362