Various settings that make Firefox behave when testing over Bidi. The
settings are copied from
ea36b7b1f0/packages/browsers/src/browser-data/firefox.ts (L190-L402).
Unlike Playwright bundled version, we write the settings into `user.js`
in the profile folder before launching the browser.
This pull request introduces initial support for the WebDriver BiDi
protocol in Playwright. The primary goal of this PR is not to fully
implement BiDi but to experiment with the current state of the
specification and its implementation. We aim to identify the biggest
gaps and challenges that need to be addressed before considering BiDi as
the main protocol for Playwright.
