This changes PlaywrigtServer to serve connections like `ws://localhost:3333/?browser=chromium`:
- launches the browser;
- talks `browserType.connect`-style protocol over websocket;
- compatible with `connectOptions` fixture.
```js
await playwright.chromium.connect({ wsEndpoint: 'ws://localhost:3333/?browser=chrome' });
```
This patch introduces 109 "#smoke" tests - a subset of tests that makes
sure that basic Playwright functionality works. This set is loosely
defined; feel free to add/remove tests to the set. The only goal is to
keep this set minimal & fast to run.
I tried to pick tests so that various parts of Playwright functionality
are exercised.
