Converts ConferenceUrl to a class and binds an instance to the global
APP variable, as requested by HTerezov.

We need to make sure that on the page reload all original parameters
used to load the conference are preserved. New modules helps to manage
different types of conference URLs like the one used for invites and
the one for reloading the page.

Enable ESLint on jitsi-meet with the same configuration and the same
goals as in lib-jitsi-meet.

Use location.href instead of location.pathname to make the URL absolute

This reverts commit 3d5af92c7a.