Fix some wording with more details, and make sure a path exists

[absltkaos]

• There was some poor wording that has been fixed
• Added a path_exists function for checking if a path exists.
• Check that /home/sovrin exists. Previously the script just checked that the mount point where the path would have been, existed.
• Provide more information on which actual mount point, and device were checked for rule compliance based on the path in a rule