Add random timing option to Random Mode

Great work on a great extension, @alexander255. This is obviously the clear successor to Random Agent Spoofer. Especially like the clean interface.

I appreciate you adding the ability to randomly change user agents. I wonder if you would consider one more small tweak? RAS not only allowed one to randomly change UAs but to the make the time between changes itself be randomized.

Having the UA change like clockwork every X minutes is itself an unusual and strong signal detectable by nosy trackers. Having the period be randomized at least lets one's browser appear a bit more like actual different users after the change.

You could have the time range reside in a preference or hardcode your own; between 1 and 30 minutes, for example. What do you think?