Add clear_existing parameter to restore_from_file
Add clear_existing parameter to restore_from_file

For use from targetcli, we want to make restoring a config when there
already is a config require extra confirmation.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

cvubrugier/rtslib-fb,agrover/rtslib-fb,mikenawrocki/rtslib-fb,mikenawrocki/rtslib-fb