In both applications, display the SQL statement that failed to parse.
For the REPL, ensure the REPL prompts the user for another statement.
For SQLStudio, we don't continue executing the script as it likely does
not make sense to run statements that come after a failed statement.
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 :^)
