Have added a little bit more context to the error messages that occur
when if starship is unable to setup the logger. This should hopefully
make it a bit easier to work out why starship can't setup the logger.
This creates a custom logger for the log crate which logs everything to a file (/tmp/starship/session_$STARSHIP_SESSION_KEY.log) and it logs everything above Warn to stderr, but only if the log file does not contain the line that should be logged resulting in an error or warning to be only logged at the first starship invocation after opening the shell.
