Implement `route(url, handler[, options])`

[robingustafsson]

Add support for BrowserContext.route(url, handler[, options]), to enable request interception allowing any request initiated in the browser context to be modified. A request with a matching URL will stall until continued, fulfilled or aborted.

Relevant links:

• Playwright docs: https://playwright.dev/docs/api/class-browsercontext#browser-context-route
• xk6-browser code starting point: https://github.com/grafana/xk6-browser/blob/main/common/browser_context.go#L230
• Playwright code: https://github.com/microsoft/playwright/blob/master/packages/playwright-core/src/client/browserContext.ts#L276
• Playwright tests: https://github.com/microsoft/playwright/blob/master/tests/browsercontext-route.spec.ts

Tasks:

• [ ] Map Route in the mapping layer.

[tmc]

Relatedly, I think this should be exposed on Page as well.

[inancgumus]

@tom-miseur: This is essentially a way to intercept requests before they get sent, which is useful for setting URL/route-specific headers. With page.setExtraHttpHeaders. You often run into CORS issues as the headers are applied across all requests.