Add support for Firefox

[bibixx]

[bibixx]

I've done some initial investigation:

1. Migrating the Chrome extension to Firefox should be fairly easy to just make it work
   1. Firefox doesn't support background.service_worker, we need to change it to background.scripts
   2. Firefox doesn't support externally_connectable (I think we can safely delete it)
   3. In background.ts we are retrieving 2 enums from chrome.declarativeNetRequest. This property doesn't seem to exist on Firefox and those 2 enums aren't defined so we need to define them manually
   4. There seems to be a major delay between logging in and redirecting user back to the Zium's site (some permission issues?)
   5. We need to extend the timeout much more for the getVersion function as it timed out too quickly
   6. When I was using the development version I had to manually allow permissions to each of the sites' urls. Need to check if we can do it with some better UX
2. The whole app seems to be super laggy on Firefox 😕 Not sure what can we do about it

   Warning This is a potential blocker for the implementation of the Firefox extension. If the performance will continue to be subpar, then a Firefox extension won't be created