chore(bidi): Handle headers properly in BiDi network.continueRequest

[juliandescottes]

Headers should be converted to valid bidi request headers.

Should fix the following tests with bidi:
page/page-request-continue.spec.ts :: continue should delete headers on redirects
page/page-request-continue.spec.ts :: continue should propagate headers to redirects
page/page-request-continue.spec.ts :: propagate headers cross origin redirect after interception

[github-actions]

Test results for "tests 1"

7 flaky

⚠️ [firefox-library] › tests/library/tracing.spec.ts:432:14 › should produce screencast frames crop @firefox-ubuntu-22.04-node18
⚠️ [firefox-page] › tests/page/page-evaluate.spec.ts:403:3 › should throw for too deep reference chain @firefox-ubuntu-22.04-node18
⚠️ [playwright-test] › tests/ui-mode-test-ct.spec.ts:59:5 › should run component tests after editing test @macos-latest-node18-1
⚠️ [chromium-library] › tests/library/popup.spec.ts:264:3 › should not throw when click closes popup @ubuntu-20.04-chromium-tip-of-tree
⚠️ [playwright-test] › tests/ui-mode-test-ct.spec.ts:59:5 › should run component tests after editing test @ubuntu-latest-node20-1
⚠️ [webkit-library] › tests/library/browsercontext-reuse.spec.ts:50:1 › should reset serviceworker @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/browsertype-launch.spec.ts:72:3 › should reject if executable path is invalid @webkit-ubuntu-22.04-node18

37545 passed, 648 skipped
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Merge workflow run.

[yury-s]

Awesome!