This lets us bubble up errors from `LibIMAP::Client::send_command()`,
which can happen if the connection hangs or is taking a long time, and
the user closes Mail.
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 :^)
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
You now cannot get an unconnected LibIMAP::Client, but you can still
close it. This makes for a nicer API where we don't have a Client object
in a limbo state between being constructed and being connected.
This code still isn't as nice as it should be, as TLS::TLSv12 is still
not a Core::Stream::Socket subclass, which would allow for consolidating
most of the TLS/non-TLS code into a single implementation.
