NVSHAS-9426 Add hostPath for scanner to helm chart

[venkateshjayagopal]

Users can pass volumes and volumeMounts using override as below,

neuvector@Host-01-RKE2:~/test/neuvector-helm-vj/charts/core$ cat override.yaml
cve:
  scanner:
    volumes:
      - name: scan-cache
        hostPath:
          path: /tmp/
          type: ""
    volumeMounts:
      - mountPath: /tmp/images/caches
        name: scan-cache

[holyspectral]

LGTM. You may also want to add some description in README.md, but this is not blocking this PR.