Extend TSM backup driver to support backup of file based volumes,
as well as restore and delete of the backups. This in addition
to the current block based volume support. This involves determining
the type of volume this is requested to be backed up, and modifying
the dsmc command options accordingly. When a volume is backed
up, the backup mode and backup path are saved in the backup
service_metadata for use on restore and delete operations.
This commit includes some further refactoring based on pylint
feedback and system testing.