Fix axe accessibility test violations compare

[mohanqxf2]

I have updated the following to the test_accessibility.py script:

• Changed ‘test_obj.conditional_write’ to ‘test_obj.log_result’
• Updated the logic to fetch only violations[] section from the axe_run results, compare it with snapshot_output.json file violations[] section, and print the results if any violations are found.
• Updated snapshot_util.py with load and save snapshot file.

To run under tests/ dir: python -m pytest test_accessibility.py