Implement table and column checker

[Vinoryz]

This pull request improves the robustness of the photosDbexif.py artifact extraction script by adding checks for the existence of required tables and columns in the Photos.sqlite database before processing. This helps prevent runtime errors and provides clearer logging when expected schema elements are missing.

Schema validation enhancements:

• Added checks to ensure the required tables (ZASSET, ZADDITIONALASSETATTRIBUTES) exist in the database before proceeding with extraction. Missing tables are logged, and the file is skipped if any are absent.
• Added checks to ensure specific columns are present in the required tables. Missing columns are logged, and the file is skipped if any are absent.
• Imported the helper functions does_table_exist_in_db and does_column_exist_in_db to facilitate these schema checks.