chore(bidi): add support for page.requestGC() in Firefox

[hbenl]

This PR implements page.requestGC() using TestUtils.gc().
Fixes the test "should work" in page/page-request-gc.spec.ts in Firefox.

[github-actions]

Test results for "tests 1"

3 failed
❌ [playwright-test] › playwright.ct-react.spec.ts:600 › should not add React import to minified .js file that already imports React after closing brace @macos-latest-node20
❌ [playwright-test] › playwright.spec.ts:485 › should work with video: on-first-retry @macos-latest-node20
❌ [playwright-test] › playwright.trace.spec.ts:137 › should not throw with trace: on-first-retry and two retries in the same worker @macos-latest-node20

4 flaky

⚠️ [chromium-library] › library/inspector/cli-codegen-pick-locator.spec.ts:35 › should update locator highlight `@ubuntu-22.04-chromium-tip-of-tree`
⚠️ [chromium-page] › page/page-request-continue.spec.ts:754 › propagate headers cross origin redirect after interception `@ubuntu-22.04-chromium-tip-of-tree`
⚠️ [chromium-library] › library/tracing.spec.ts:432 › should produce screencast frames fit `@chromium-ubuntu-22.04-node20`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:700 › should indicate current test status `@macos-latest-node20`

34270 passed, 662 skipped

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Merge workflow run.

[github-actions]

Test results for "MCP"

36 failed
❌ [firefox] › mcp/cli-core.spec.ts:114 › uncheck @mcp-ubuntu-latest
❌ [firefox] › mcp/cli-webstorage.spec.ts:43 › localstorage-list shows items @mcp-ubuntu-latest
❌ [firefox] › mcp/files.spec.ts:106 › clicking on download link emits download @mcp-ubuntu-latest
❌ [webkit] › mcp/cli-webstorage.spec.ts:123 › sessionstorage-delete removes item @mcp-ubuntu-latest
❌ [chrome] › mcp/console.spec.ts:198 › console log file is created on snapshot @mcp-windows-latest
❌ [chrome] › mcp/network.spec.ts:75 › network log file is returned on snapshot @mcp-windows-latest
❌ [chrome] › mcp/network.spec.ts:118 › network log file separates requests and assets @mcp-windows-latest
❌ [chrome] › mcp/network.spec.ts:168 › network log file stores method and status @mcp-windows-latest
❌ [chrome] › mcp/network.spec.ts:209 › new network log file after navigation @mcp-windows-latest
❌ [chrome] › mcp/session-log.spec.ts:22 › session log should record tool calls @mcp-windows-latest
❌ [chromium] › mcp/console.spec.ts:198 › console log file is created on snapshot @mcp-windows-latest
❌ [chromium] › mcp/network.spec.ts:75 › network log file is returned on snapshot @mcp-windows-latest
❌ [chromium] › mcp/network.spec.ts:118 › network log file separates requests and assets @mcp-windows-latest
❌ [chromium] › mcp/network.spec.ts:168 › network log file stores method and status @mcp-windows-latest
❌ [chromium] › mcp/network.spec.ts:209 › new network log file after navigation @mcp-windows-latest
❌ [chromium] › mcp/session-log.spec.ts:22 › session log should record tool calls @mcp-windows-latest
❌ [firefox] › mcp/console.spec.ts:198 › console log file is created on snapshot @mcp-windows-latest
❌ [firefox] › mcp/files.spec.ts:106 › clicking on download link emits download @mcp-windows-latest
❌ [firefox] › mcp/network.spec.ts:75 › network log file is returned on snapshot @mcp-windows-latest
❌ [firefox] › mcp/network.spec.ts:118 › network log file separates requests and assets @mcp-windows-latest
❌ [firefox] › mcp/network.spec.ts:168 › network log file stores method and status @mcp-windows-latest
❌ [firefox] › mcp/network.spec.ts:209 › new network log file after navigation @mcp-windows-latest
❌ [firefox] › mcp/session-log.spec.ts:22 › session log should record tool calls @mcp-windows-latest
❌ [webkit] › mcp/console.spec.ts:198 › console log file is created on snapshot @mcp-windows-latest
❌ [webkit] › mcp/network.spec.ts:75 › network log file is returned on snapshot @mcp-windows-latest
❌ [webkit] › mcp/network.spec.ts:118 › network log file separates requests and assets @mcp-windows-latest
❌ [webkit] › mcp/network.spec.ts:168 › network log file stores method and status @mcp-windows-latest
❌ [webkit] › mcp/network.spec.ts:209 › new network log file after navigation @mcp-windows-latest
❌ [msedge] › mcp/console.spec.ts:198 › console log file is created on snapshot @mcp-windows-latest
❌ [msedge] › mcp/network.spec.ts:75 › network log file is returned on snapshot @mcp-windows-latest
❌ [msedge] › mcp/network.spec.ts:118 › network log file separates requests and assets @mcp-windows-latest
❌ [msedge] › mcp/network.spec.ts:168 › network log file stores method and status @mcp-windows-latest
❌ [msedge] › mcp/network.spec.ts:209 › new network log file after navigation @mcp-windows-latest
❌ [msedge] › mcp/session-log.spec.ts:22 › session log should record tool calls @mcp-windows-latest
❌ [firefox] › mcp/cli-webstorage.spec.ts:87 › sessionstorage-list shows no items when empty @mcp-macos-15
❌ [firefox] › mcp/files.spec.ts:106 › clicking on download link emits download @mcp-macos-15

4535 passed, 135 skipped

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Merge workflow run.