[tests]: run E2E tests in multiple browsers

[koebel]

Since oCIS supports multiple browser option, these same set of browser options should be used for oCIS extensions.

code sample from ocis web (shared by Amrita)

  const browsers: Record<string, () => Promise<Browser>> = {
    firefox: async (): Promise<Browser> => await firefox.launch(browserConfiguration),
    webkit: async (): Promise<Browser> => await webkit.launch(browserConfiguration),
    chrome: async (): Promise<Browser> =>
      await chromium.launch({ ...browserConfiguration, channel: 'chrome' }),
    chromium: async (): Promise<Browser> => await chromium.launch(browserConfiguration)
  }

Originally posted by @amrita-shrestha in #12 (comment)