Reset species output paths when deleting all species jobs (#686)

When we `delete_all_species_jobs`, for example after switching a TS
guess to something better and we no longer need the sp, freq, etc jobs
of the previous TS, we must also reset the `output` dict of the
`Scheduler` object, so that all paths are empty. Note that for `irc` we
have two paths, forward and reverse, so we treat it differently (see
[here
](https://github.com/ReactionMechanismGenerator/ARC/blob/main/arc/scheduler.py#L101)the
structure of the output dict)

arc/scheduler.py

@@ -3381,6 +3381,7 @@ def delete_all_species_jobs(self, label: str):
                     logger.info(f'Deleted job {job_name}')
                     job.delete()
         self.running_jobs[label] = list()
+        self.output[label]['paths'] = {key: '' if key != 'irc' else list() for key in self.output[label]['paths'].keys()}
 
     def restore_running_jobs(self):
         """