InodeWatcherFlags is an enumeration from the Kernel. To avoid using it
outside of Serenity, add a FileWatcherFlags for FileWatcher, much like
we already have FileWatcherEvent::Type.
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 :^)
Plumbs synchronous calls for adding and removing group entries to
config files. This is useful for services like SystemServer which
default to group names for executable paths, and for removing all
keys at once.
