x402 support

[Gallaecio]

Built on top of zytedata/python-zyte-api#89.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.90%. Comparing base (fe819a2) to head (ee4fcce).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #261      +/-   ##
==========================================
+ Coverage   97.88%   97.90%   +0.01%     
==========================================
  Files          14       14              
  Lines        1800     1817      +17     
  Branches      339      343       +4     
==========================================
+ Hits         1762     1779      +17     
  Misses         16       16              
  Partials       22       22              

Files with missing lines	Coverage Δ
scrapy_zyte_api/handler.py	96.13% <100.00%> (+0.23%)	⬆️
scrapy_zyte_api/utils.py	100.00% <100.00%> (ø)

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[kmike]

I wonder if we should downplay it a bit for now - add a separate section about x402, and add a link to it, while keeping it outside of the "main" setup flow.

[Gallaecio]

7d3e6a7 ?