[py] Add high-level BiDi network request handler API

[AutomatedTester]

🔗 Related Issues

💥 What does this PR do?

Adds the doc-aligned high-level request interception API to driver.network (Phase 1 of the BiDi Protocol API Design):

• add_request_handler(callback) / add_request_handler(url_patterns, callback) with glob URL patterns (*, **, ?) — translated to browser-side BiDi UrlPatterns where expressible, with automatic fallback to intercept-all plus Python-side matching
• Request now exposes method, headers, cookies, body, resource_type, plus fail(), provide_response(status, headers, body) and set_url/set_method/set_headers/set_cookies/set_body mutators
• After all matching handlers run, the outcome is reconciled into exactly one BiDi command per request: fail > provideResponse > continueRequest with mutations > continueRequest — observer-only handlers no longer stall the page, and handler exceptions are logged without hanging the request
• Reconciliation only touches requests blocked by this registry's intercepts (checked via the event's intercepts field), so legacy handlers are unaffected

🔧 Implementation Notes

• The implementation lives in a new static helper module py/private/_network_handlers.py, staged verbatim into the generated selenium.webdriver.common.bidi package via create-bidi-src extra_srcs (same mechanism as _event_manager.py). This keeps the logic lintable, formattable and unit-testable as real code instead of string blobs in the enhancement manifest.
• The enhancement manifest now only carries thin glue: a re-export import (so bidi.network.Request stays importable), registry init, and polymorphic dispatch in add_request_handler/remove_request_handler.
• Backwards compatibility: the legacy phase-based forms (add_request_handler("before_request", cb, url_patterns=[...]), two-arg remove_request_handler) are unchanged; unknown event-name strings still raise ValueError (a heuristic distinguishes URL globs from event-name tokens). All pre-existing unit tests pass unmodified in behavior.

🤖 AI assistance

• AI assisted (complete below)
  • Tool(s): Claude Code
  • What was generated: _network_handlers.py, manifest/BUILD glue, and unit tests, from the BiDi Protocol API Design doc
  • I reviewed all AI output and can explain the change

💡 Additional Considerations

• High-risk area: wire-level network interception semantics — new reconciliation applies to the new-style handlers only; legacy paths are preserved byte-for-byte.
• Follow-up phases planned: response handlers (add_response_handler), callback-based authentication handlers with cancel(), extra-headers API, and Script module alignment.
• Cross-binding parity (Java/Ruby/JS) for the doc-aligned naming is follow-up work.
• A live-browser test in py/test/selenium/webdriver/common/bidi_network_tests.py is a sensible follow-up; this PR covers the logic with 21 new unit tests (bazel test //py:unit → 27/27 pass).

🔄 Types of changes

• New feature (non-breaking change which adds functionality and tests!)

[diemol]

Adds the doc-aligned high-level request interception API to driver.network (Phase 1 of the BiDi Protocol API Design):

Which doc?

[AutomatedTester]

Adds the doc-aligned high-level request interception API to driver.network (Phase 1 of the BiDi Protocol API Design):

Which doc?

https://docs.google.com/document/d/1icS4UmN6-x6LMENux7d9MDVpD30OQ9ZcjNIYLL94vFo/edit?tab=t.pa5y6ld2l59k#heading=h.620lcimekkqc that was shared from @titusfortner