Privacy Browser Android

To do this, `user_agent_entry_values` would contain entries like `Firefox on Android`. Then there would be a second `string-array` that would contain the actual user agents. The user agents would be pulled from the second `string-array` at runtime. This would allow a user to set a particular user-agent and have it autoupdate (as frequently as Privacy Browser is released).

Of course, this would entail updating the user agents with every release of Privacy Browser, as opposed to the couple of times per year that happens now. ;)