Support glob patterns in referenced license files

[SidheshwarSarangal]

Fixes #4276

This adds support for glob patterns in license rule
referenced_filenames, including directory patterns such as
licenses/*.

The change:

• preserves the existing fast path for exact filenames;
• matches glob patterns one path segment at a time, preventing wildcards
  from crossing directory boundaries;
• resolves matches through the existing resource-location rules;
• aggregates all matching referenced license files while avoiding
  duplicates;
• adds a regression test for a directory glob resolving multiple files.

Tests:

• tests/licensedcode/test_plugin_license_detection.py: 21 passed
• tests/packagedcode/test_license_detection.py: 19 passed