Catch also YT links in the address bar

[360fun]

In relation to #618.

Would be useful to have an option to open FreeTube also when the user inserts YT links in the browser address bar.

UI/UX

1. should be optional
2. could have a "countdown" option to allow the user to open the original link without disabling the extension: if the user doesn't click "Open in YouTube" when it reaches 0, FreeTube handles the link automatically

[360fun]

This could be an alternative/fallback to #672. The action won't be direct but with a call to the browser in the middle: anyway the final result will be see the video opening in FreeTube. ;)