[Feature] Add preprocessed as remove intermediate file option

[JoeZiminski]

preprocessed was an option to delete_intermediate_files but becase the sorting_data class holds Spikeinterface recording objects that are not closed, an error occurs when trying to delete e.g.:

[WinError 32] The process cannot access the file because it is being used by another process: 'C:\\data\\ephys\\test_data\\steve_multi_run\\1119617\\time-short\\derivatives\\1119617\\1119617_LSE1_shank12_g0\\preprocessed\\si_recording\\traces_cached_seg0.raw'      ```

As a workaround, the hacky below code was used however it is proving unstable

if "preprocessed" in delete_intermediate_files:
    # remove the existing link to the preprocessed data binary.
    # wait time of 5 s is arbitrary.
    # TODO: this feels very hacky. Can unlink the memory map from the segment?
    # Ask SI.
    del sorting_data.data
    gc.collect()
    time.sleep(5)

    if sorting_data.get_preprocessing_path(run_name).is_dir():
        shutil.rmtree(sorting_data.get_preprocessing_path(run_name))

The correct solution is to use SI to close the memmaped file link. However, I can't find on their API - make an issue.