M #-: Assert that fstab config matches existing filesystems (fix)

[sk4zuzu]

No description provided.

[fpolanco-one]

Description:
Existing mounted datastore filesystems cannot be reformatted by one-deploy, actual code will mount the datastore mountpoint in fstab, and upon reboot, the host will be held in emergency mode because a mountpoint cannot be fulfilled due to incorrect filesystem. Example: existing FS: VFAT, specified FS: XFS.

[sk4zuzu]

Yes, if the device is already mounted one-deploy will skip it even if force flag is provided, as we cannot mkfs on a device that is mounted and we cannot really auto-unmount as we would have to scan running processes that hold the mountpoint and kill them (we can't make that decision in general).

This PR simply adds missing (arguably) feature of the mount module, it just detects the discrepancy and gives some time to the user so the mismatch can be corrected.