core: extract parameters initialization to seperate method

Extract long blocks of code that initialize command parameters from
MoveOrCopyTemplateCommand#moveOrCopyAllImageGroups and
AddVmFromTemplateCommand#addVmImages methods to separate methods in
order to make the code more concise and readable

Change-Id: I7328e84274fd9ba9f109608600da66c6308ec0b9
Signed-off-by: Arik Hadas <ahadas@redhat.com>