Bug 1884975

Description of problem:
VM import from VMware to RHV via api, using "name" for the source storage,
causes a crash:
VM import remain in 5%. VM import resource report validation completed.
VM import controller log report:
"panic: runtime error: invalid memory address or nil pointer dereference [recovered]
        panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1ebe93b]

goroutine 1394 [running]:
k8s.io/apimachinery/pkg/util/runtime.HandleCrash(0x0, 0x0, 0x0)" 

Version-Release number of selected component (if applicable):
CNV-2.5

Additional info:
Source (VMware) storage name was used due to this doc bug:
Bug 1884970 - [v2v][Doc][VMware to CNV VM import API] Storage Mapping: Source storage name should change to storage id

Additional info - How it was tested:
Secret:
------
cat <<EOF | oc create -f -
---
apiVersion: v1
kind: Secret
metadata:
 name: vmw-secret
type: Opaque
stringData:
 vmware: |-
   # API URL of the vCenter or ESXi host
   apiUrl: "https://<Vcenter IP address>/sdk"
   # Username provided in the format of username@domain.
   username: <username>
   password: <password>
   # The certificate thumbprint of the vCenter or ESXi host, in colon-separated hexidecimal octets.
   thumbprint: 31:14:..
EOF

External mapping
----------------

cat <<EOF | oc create -f -
apiVersion: v2v.kubevirt.io/v1beta1
kind: ResourceMapping
metadata:
 name: example-vmware-resourcemappings
 namespace: default
spec:
  vmware:
    networkMappings:
    - source:
        name: VM Network # map network name to network attachment definition
      target: 
        name: pod
      type: pod
    storageMappings:
    - source:
        name: <VMware datastore name>   <======== Here use a name instead of ID
      target: 
        name: nfs
EOF

VM import create
----------------
cat <<EOF | oc create -f -
apiVersion: v2v.kubevirt.io/v1beta1
kind: VirtualMachineImport
metadata:
  name: vmware-import-1
  namespace: default
spec:
  providerCredentialsSecret:
    name: vmw-secret
    namespace: default # optional, if not specified, use CR's namespace
  resourceMapping:
    name: example-vmware-resourcemappings
    namespace: default
  targetVmName: vmw-import
  startVm: false
  source:
    vmware:
      vm:
        id: 42037aff-4d6f-cf89-7979-e98cbc406c0e
EOF