setroubleshoot.util: Catch exceptions from sepolicy import
    
    Fixes the following bt on SELinux disable system:
    
      File "src/setroubleshoot/util.py", line 370, in <module>
        file_types = get_all_file_types()
      File "/usr/lib/python3/dist-packages/sepolicy/__init__.py", line 960, in get_all_file_types
        file_types = list(sorted(info(ATTRIBUTE, "file_type"))[0]["types"])
      File "/usr/lib/python3/dist-packages/sepolicy/__init__.py", line 224, in <genexpr>
        return ({
      File "/usr/lib/python3/dist-packages/setools/typeattrquery.py", line 65, in results
        for attr in self.policy.typeattributes():