config edit used the whole of $EDITOR as the program name, so a value
with arguments such as "code --wait" or "emacsclient -t" failed with
"executable file not found". It now runs $EDITOR the way git does:
sh -c '<editor> "$@"' with the config path as a separate argument, so
the editor's own arguments and quoting work and a path with spaces
reaches it whole. A test runs config edit with an $EDITOR carrying an
argument on a config path that contains a space.
Model: opus-5-5
sneak