Add support for skipping specified directories during index generation

[onairmarc]

This pull request enhances the index generation rule to allow certain directories to be explicitly skipped during index file creation, even if they are listed in the directories to process. The changes introduce a new skipDirectories option and update the logic to consistently honor this exclusion across recursive and non-recursive operations.

Configuration improvements:

• Added a new skipDirectories property to the IndexGenerationConfig interface, allowing users to specify directories that should always be excluded from index generation, regardless of their presence in the directories list.

Index generation logic updates:

• Updated the generateSingleDirectoryIndex, generateIndexExportRecursive, and generateIndexExport methods to accept and utilize a set of skip paths, ensuring that specified directories are consistently excluded during index creation. [1] [2] [3]
• Modified directory processing in the main execution flow to resolve and check skip paths before triggering index generation, preventing unnecessary processing of excluded directories.

Directory traversal enhancements:

• Improved recursive directory traversal logic to check and skip directories listed in skipDirectories at every level, ensuring exclusions are respected throughout nested structures. [1] [2]