Support *url.URL in flags as well as arguments

[FollowTheProcess]

Summary

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.03%. Comparing base (33c6f35) to head (a099a72).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/flag/flag.go	75.00%	3 Missing and 1 partial ⚠️
internal/arg/arg.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #201      +/-   ##
==========================================
- Coverage   85.15%   85.03%   -0.12%     
==========================================
  Files           9        9              
  Lines        1617     1631      +14     
==========================================
+ Hits         1377     1387      +10     
- Misses        172      175       +3     
- Partials       68       69       +1     

☔ 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.