core: import cleanup in VDSCommand parameters

Cleaned up the imports in the org.ovirt.engine.core.common.vdscommands
package:
* Replaced explicit inline FQCNs with imports
* Replaced * imports with FQCN imports

Change-Id: I35c668babca742020c61ac4d15fc47d10794323d
Signed-off-by: Allon Mureinik <amureini@redhat.com>