virt-launcher, converter: Refactor network indexing
virt-launcher, converter: Refactor network indexing

- The CNI indexing is not used and therefore removed.
- Extracted to two functions: validation and indexing.

Signed-off-by: Edward Haas <416ab6a6c3e37a8cab0d365516e79cce8f9be5ad@redhat.com>

davidvossel/kubevirt,davidvossel/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,stu-gott/kubevirt,stu-gott/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt