fix: allow specifying user agent in v2 osvscanner package

[Ly-Joey]

Users can specify a user agent with ExperimentalScannerActions.RequestUserAgent.

Resolves: #2420

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.82%. Comparing base (d57b6b6) to head (292b8f1).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2433      +/-   ##
==========================================
- Coverage   67.84%   67.82%   -0.03%     
==========================================
  Files         172      172              
  Lines       13284    13292       +8     
==========================================
+ Hits         9013     9015       +2     
- Misses       3567     3571       +4     
- Partials      704      706       +2     

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[another-rex]

LGTM!