feat(electron): emit dialog event for main-process dialog API

[yury-s]

Summary

Adds two events on ElectronApplication for intercepting Electron's main-process dialog API:

• filechooser (ElectronFileChooser) for dialog.showOpenDialog / dialog.showSaveDialog — setFiles(paths) / cancel().
• dialog (ElectronDialog) for dialog.showMessageBox / dialog.showCertificateTrustDialog — accept(result) / dismiss().

The hook is installed via CDP Runtime.evaluate against the Node session, so it works for both packaged and non-packaged Electron apps. Patched dialog methods stream call payloads back through a Runtime.addBinding binding and await results from the Playwright server.

Fixes #8278

[dgozman]

Looking at this in details, I don't think we provide more value than:

await app.evaluate(({ dialog }, paths) => {
  dialog.showOpenFileDialogSync = () => paths;
}, ['/path/to/file']);

Perhaps we just need some docs, and that's it?

[dgozman]

Why do we need to return options? Are there any particular options we care about? Perhaps explicit isMultiple() to match the browser API?

[yury-s]

The list of options is pretty reach in electron, it might be useful for asserting behavior/filtering the dialogs, things like defaultPath, filters, openFiles etc. We can drop that completely and expose isMultiple() to match web api, or just wait for user reports.

[github-actions]

Test results for "MCP"

7181 passed, 1113 skipped

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Merge workflow run.

[github-actions]

Test results for "tests 1"

4 flaky

⚠️ [chromium-library] › library/inspector/recorder-api.spec.ts:120 › should type `@ubuntu-22.04-chromium-tip-of-tree`
⚠️ [chromium-library] › library/video.spec.ts:719 › screencast › should work with video+trace `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/video.spec.ts:719 › screencast › should work with video+trace `@chromium-ubuntu-22.04-node20`
⚠️ [chromium-library] › library/video.spec.ts:476 › screencast › should capture static page in persistent context @smoke `@chromium-ubuntu-22.04-node22`

42060 passed, 850 skipped

---

Merge workflow run.

[yury-s]

Looking at this in details, I don't think we provide more value than:

await app.evaluate(({ dialog }, paths) => {
  dialog.showOpenFileDialogSync = () => paths;
}, ['/path/to/file']);

Perhaps we just need some docs, and that's it?

For simple cases yes, but for more complex where the users my want to have some logic in playwright we are currently missing out on ElectronApplication.exposeBinding, it only exists on the renderer contexts, maybe we should expose it for the node context too?

[yury-s]

Docs-only approach: #40952.