cfgparse: Write custom scripts for i3-sensible-terminal

cfgparse: Write custom scripts for i3-sensible-terminal

This workaround is necessary for terminal emulators which parse -e in a
different way: some accept a list of arguments (-e command arg1 arg2 …),
some accept only one argument (-e "command arg1 arg2 …"). Therefore, we
just create a script and pass that as the one and only argument.