Improves access logging and face detection tests

[Nandika-A]

Description

Additional features are added in test functions: test_access_logging:

1. Check whether the file exists at the correct path
2. Clean up the log file before running the test

test_face_detection:

1. Check if the image is not entirely black
2. Check for Detected Faces Being Non-Overlapping

Related Issue

Fixes #8

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Motivation and Context

How Has This Been Tested?

All tests are successful after running unittest.

Screenshots (if appropriate):

Checklist:

• [x] I have registered myself at Contrihub website.
• [x] My code follows the code style of this project.
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] Any dependent changes have been merged and published in downstream modules
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

Test Configuration:

• Firmware version:
• Hardware:
• Toolchain:
• SDK:

[Nandika-A]

@sanskaromar I have removed the test for black images. Please check if any other changes are required.