One-by-one file insert to avoid transaction timeout when inserting large files

[ttngu207]

This pull request refactors how result files are inserted into the database within the element_array_ephys/spike_sorting/si_spike_sorting.py module. Instead of batch-inserting file records, the code now inserts each file individually as it is discovered. This change enhances clarity and may improve error handling or logging for individual file insertions.

Refactoring of file insertion logic:

• Changed from batch insertion (self.File.insert([...])) to per-file insertion (self.File.insert1(...)) for result files in the _run_sorter method.
• Applied the same per-file insertion pattern in the _sorting_analyzer_compute method for files in the analyzer output directory.
• Updated the _export_report method to insert report files individually for each file found in the relevant report directories.