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 :^)
This is a naive-but-somewhat-functional initial implementation of
HTML Storage.
Note that there is no persistence yet, everything is in-process only,
and one local Storage object per origin.
