feat: configFile: false to disable config file loading

[kricsleo]

resolves #236

This PR brings back support for configFile: false.

[codecov]

Codecov Report

Attention: Patch coverage is 61.70213% with 18 lines in your changes missing coverage. Please review.

Project coverage is 77.79%. Comparing base (42d9697) to head (689ce39).
Report is 131 commits behind head on main.

Files with missing lines	Patch %	Lines
src/watch.ts	0.00%	11 Missing ⚠️
src/loader.ts	80.55%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #245      +/-   ##
==========================================
+ Coverage   76.92%   77.79%   +0.87%     
==========================================
  Files           7        6       -1     
  Lines         806      635     -171     
  Branches       80      124      +44     
==========================================
- Hits          620      494     -126     
+ Misses        184      141      -43     
+ Partials        2        0       -2     

☔ 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.