Before, navigator.platform would always report the platform as "Serenity
OS", regardless of whether or not that was true. It also did not include
the architecture, which Firefox and Chrome both do. Now, it can report
either "Linux x86_64" or "SerenityOS AArch64".
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
Get rid of the bespoke NavigatorObject class and use the modern IDL
strategies for creating platform objects to re-implement Navigator and
its associcated mixin interfaces. While we're here, implement it in a
way that brings WorkerNavigator up to spec :^)
