vmware: Use virDomainObjListFindBy{UUID|ID}Ref

vmware: Use virDomainObjListFindBy{UUID|ID}Ref

For vmwareDomObjFromDomainLocked and vmwareDomainLookupByID
let's return a locked and referenced @vm object so that callers
can then use the common and more consistent virDomainObjEndAPI
in order to handle cleanup rather than needing to know that the
returned object is locked and calling virObjectUnlock.

The LookupByName already returns the ref counted and locked object,
so this will make things more consistent.

For vmwareDomainUndefineFlags and vmwareDomainShutdownFlags since
virDomainObjListRemove will return an unlocked object, we need to
relock before making the EndAPI call.

Signed-off-by: John Ferlan <jferlan@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>