Add a new endpoint for removing datasets or files from cache

[elmiomar]

This PR introduces a new removeFromCache() method in the CacheManagementController is designed to handle DELETE requests for removing either an entire dataset or specific files within a dataset from the cache. Here's a detailed breakdown of its functionality:

• checks if the cache manager (PDRCacheManager in this context) is operational by calling _checkForManager()
• extracts the dataset identifier (dsid) from the URL path variable
• determines removal scope:
  • if no specific file path is provided or if the path refers to the dataset as a whole, the method removes the entire dataset from the cache
  • if a specific file path is provided, the method removes just the specified files within the dataset
• retrieves Cache objects: depending on the removal scope in the previous step, it uses either selectDatasetObjects() or selectFileObjects() method from PDRCacheManager to retrieve a list of CacheObjects that represent the dataset or specific files within it
• for each CacheObject retrieved in the previous step, it calls the uncache() method to remove the object from the cache. This removal leverages the inherited uncache() functionality from BasicCacheManager through PDRCacheManager.

[elmiomar]

Updates:

• Enhanced the "remove objects from cache" endpoint logic to include the :cached selector for more accurate cache management.
• Identified and fixed a bug in the "get from cache" endpoint where a ResourceNotFound exception failed to trigger for an empty files list; this was because empty list verification was done before the completion of the files selection process.
• Added a unit test to cover a new scenario for the "remove from cache" endpoint.
• Confirmed that existing unit tests remain successful following the the bug fix.

Other changes introduced in this PR include:

• Removed the redundant RPARequestHandler interface and its associated implementation.
• Renamed the IRPARequestHandler interface to RPARequestHandler for clarity.
• Improved inline documentation.

[RayPlante]

This was tested end-to-end after being combined with PRs #102, #103, #106, and associated updates to the front-end RPA apps on testdata. I fully tested the endpoint for deleting data from the cache--both as individual files or as a whole dataset.