chore(bidi): add support for fetching response bodies

[hbenl]

Fixes #37218 and (at least) the following tests in Firefox:

• tests/library/browsercontext-base-url.spec.ts:
  • "should be able to match a URL relative to its given URL with urlMatcher"
• tests/library/browsercontext-credentials.spec.ts:
  • "should return resource body"
• tests/library/browsercontext-har.spec.ts:
  • "should update extracted har.zip for page"
  • "should update har.zip for context"
  • "should update har.zip for page"
  • "should update har.zip for page with different options"
• tests/library/browsertype-connect.spec.ts:
  • "launchServer > should fulfill with global fetch result"
  • "run-server > should fulfill with global fetch result"
• tests/library/har.spec.ts:
  • "should attach content"
  • "should contain http2 for http2 requests"
  • "should include content smoke"
  • "should use attach mode for zip extension"
• tests/page/frame-goto.spec.ts:
  • "should return matching responses"
• tests/page/page-event-request.spec.ts:
  • "should return response body when Cross-Origin-Opener-Policy is set"
• tests/page/page-history.spec.ts:
  • "page.reload should not resolve with same-document navigation"
• tests/page/page-network-response.spec.ts:
  • "should return text"
  • "should return uncompressed text"
  • "should wait until response completes"
  • "should return json"
  • "should return body"
  • "should return body with compression"
  • "should return body for prefetch script"
• tests/page/page-request-fallback.spec.ts:
  • "should not chain fulfill"
  • "should chain once"
• tests/page/page-request-fulfill.spec.ts:
  • "should fulfill with global fetch result"
  • "should fulfill with fetch result"
  • "should fulfill with fetch result and overrides"
  • "should return body for fulfilled responses"
• tests/page/page-request-intercept.spec.ts:
  • "should fulfill with any response"
  • "should intercept with url override"
  • "should support fulfill after intercept"
• tests/page/workers.spec.ts:
  • "should report worker script as network request"
  • "should report worker script as network request after redirect"

[github-actions]

Test results for "tests 1"

4 flaky

⚠️ [chromium-library] › library/chromium/oopif.spec.ts:284 › should click `@chromium-ubuntu-22.04-node24`
⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:1079 › cli codegen › should not throw csp directive violation errors `@firefox-ubuntu-22.04-node18`
⚠️ [firefox-library] › library/inspector/cli-codegen-3.spec.ts:226 › cli codegen › should generate frame locators (4) `@firefox-ubuntu-22.04-node18`
⚠️ [firefox-library] › library/inspector/cli-codegen-aria.spec.ts:76 › should update aria snapshot highlight `@firefox-ubuntu-22.04-node18`

46713 passed, 809 skipped

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Merge workflow run.