Fixed an issue in Infinidat driver to support host assisted migration.
And added new configuration options:
* `infinidat_snapdir_accessible` to configure access to the `.snapshot`
directory on the client side.
* `infinidat_snapdir_visible` to configure visibility of the `.snapshot`
directory on the client side.
Closes-Bug: #1992443
Signed-off-by: Alexander Deiter <adeiter@infinidat.com>
Change-Id: I29b51fcec28dd5110de6ad196ff8b67c875ce8fa