feat(google_container_node_pool): support secondary boot disks

[modular-magician]

Fixes hashicorp/terraform-provider-google/issues/17655

This PR added support for secondary boot disks to google_container_node_pool resource. This allows users to improve workload startup latency by using secondary boot disks to preload data or container images on new nodes. See Use secondary boot disks to preload data or container images for further documentation. These code changes build off a draft commit by @elfinhe, adding required configs, schema changes, and test validation.

If this PR is for Terraform, 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. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).

• 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). Added TestAccContainerNodePool_secondaryBootDisks to //third_party/terraform/services/container/resource_container_node_pool_test

• 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). From the cluster, I inspected the node pool, which led me to the node VM page showing boot and additional disk

• Read Write release notes before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

container: added `node_config.secondary_boot_disks` field to `google_container_node_pool`

Derived from GoogleCloudPlatform/magic-modules#10511