Add env option to disable part image overlay

[d-buchmann]

Fixes #369 while preserving the state as-is

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.48%. Comparing base (c445359) to head (d6bb8cb).
Report is 2 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #960      +/-   ##
============================================
- Coverage     59.73%   59.48%   -0.25%     
- Complexity     6036     6038       +2     
============================================
  Files           529      529              
  Lines         20588    20602      +14     
============================================
- Hits          12298    12256      -42     
- Misses         8290     8346      +56     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[jbtronics]

Thank you.