Add HTTP Basic Auth

[imiric]

The httpCredentials BrowserContext option doesn't seem to be working, and HTTP basic auth in general seems to be partially implemented.

Version: de8c9d2

Steps to reproduce

Run the following script:

import launcher from 'k6/x/browser';
import { sleep } from 'k6';

export default function() {
  const browser = launcher.launch('chromium', {
    headless: false,
  });
  const context = browser.newContext({
    httpCredentials: {
      username: 'user',
      password: 'pass',
    }
  });
  const page = context.newPage();

  page.goto('https://authenticationtest.com/HTTPAuth/', { waitUntil: 'load' });
  sleep(3);

  page.close();
  browser.close();
}

On de8c9d2 (#202) this fails with:

ERRO[0001] Failed to load resource: the server responded with a status of 401 ()  browser_source=network line_number=0 source=browser stacktrace="<nil>" url="chrome-error://chromewebdata/"
ERRO[0001] navigation interrupted by another one
running at reflect.methodValueCall (native)
default at file:///home/ivan/Projects/grafana/xk6-browser/examples/test-105-cdp-fetch.js:16:56(34)

Commenting out the navigation interrupted by another one line, shows the browser window and credential prompt, and the above 401 error is logged.

Implementation suggestions

This seems to require request interception with the Fetch domain, which is partially implemented here. What's missing is a call to fetch.ContinueWithAuth().

[unlikelyzero]

Currently this is a blocker for our internal performance testing as everything is (presently, but will not always be) routed through basic auth.

[imiric]

Hi @unlikelyzero, basic auth support will be released in the upcoming v0.2.0, scheduled for later this week, or you can use it now by building the extension from main.