Add Terraform support for GKE enable_nested_virtualization option

[modular-magician]

This PR adds the advanced_machine_features.enable_nested_virtualization field in node_config. It enables the user to use terraform to config nested VMs with GKE clusters.

I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description].
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Generated Terraform providers, and ran make test and make lint in the generated providers to ensure it passes unit and linter tests.
• Ran relevant acceptance tests using my own Google Cloud project and credentials (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read Write release notes before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

container: added `enable_nested_virtualization` field to `google_container_node_pool` and `google_container_cluster` resource.

Derived from GoogleCloudPlatform/magic-modules#10558