[AIOHTTPTransport] Add extra_args parameter to subscribe()

[magicmark]

The execute() and execute_batch() methods accept an extra_args parameter, which allows us to override headers per request. subscribe() was missing this parameter.

Disclosure: I used Claude Code for the initial work on this PR but have desloppified and verified it works locally.

cc @leszekhanusz

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (7fb869a) to head (d0e1a4a).
⚠️ Report is 50 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##            master      #584    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           38        40     +2     
  Lines         2908      3311   +403     
==========================================
+ Hits          2908      3311   +403     

☔ 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.

[leszekhanusz]

Thanks