feat: add support for ignored network destination type

[albertoflorez]

Summary

This PR introduces the capability to define ignored as a valid network_destination_type within the network mapping templates. This enhancement applies to both vsphere and ovirt providers.

Motivation and Context

When executing large-scale migrations via the Migration Toolkit for Virtualization (MTV) and Migration Factory, there are scenarios where specific source networks do not require a destination target (e.g., deprecated, isolated, or non-routable networks).

Previously, the template forced a fallback to pod or multus types if the network list wasn't empty, which caused validation or runtime errors during the migration planning phase. Allowing an explicit ignored type ensures that these networks are properly accounted for in the migration manifests without generating unnecessary target bindings, providing greater flexibility for automated enterprise migration pipelines.

Changes Made

• Template Logic Update (vsphere & ovirt): Added a conditional block to evaluate if network_destination_type is explicitly set to "ignored".
• Output Standardization: When a network is ignored, the template now correctly renders only type: ignored under the destination metadata block while keeping the source definition intact.
• Backward Compatibility: Preserved existing conditional logic for pod and multus network attachment definitions.

How This Was Tested

Verified that when network_destination_type: "ignored" is passed in the overrides, the generated YAML successfully maps the destination as expected:

- destination:
    type: ignored
  source:
    id: network-117
    name: none