refactor: get rid off browser.launchId, use id instead

browser.launchId was the id of the browser (generated by launcher) and browser.id was the id of the
socket. We don't care about the socket id anymore, as since cbe2851baa55312f00be420e0345283b33326266
a single browser can change its socket id.

Also, we should generate id for manually started browsers too (to enable reconnecting for them).

This basically reverts be98bce672f818ae4a994cfede5eb8e7116b3351.
WIP: use updated version of junit-reporter