batch requests in wpt

[KhafraDev]

closes #810

I have no idea how to add tests for this, but hopefully it's straightforward. This is needed for undici to use git node wpt to pull tests for its runner.

[aduh95]

Can you add a comment explaining why we're doing this? Otherwise there's a chance it gets reverted if this code is ever refactored

[aduh95]

@KhafraDev is this still needed?

[KhafraDev]

I haven't had to use git node wpt recently but I assume the issue is still present

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 80.15%. Comparing base (39f1002) to head (dfbde9d).
Report is 106 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/wpt/index.js	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #813      +/-   ##
==========================================
- Coverage   83.02%   80.15%   -2.88%     
==========================================
  Files          37       39       +2     
  Lines        4213     4635     +422     
==========================================
+ Hits         3498     3715     +217     
- Misses        715      920     +205     

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