* Add preemptible as an option to node config
* Check for preemptible in test matching functions
* Move flattenClusterNodeConfig to node_config
* Handle bools properly when comparing in cluster and node pool tests
* Use a supported image_type in cluster tests
* Add support node config for GKE node pool
* Review fixes:
- Set max items in node config schema
- Fill missing node config fields
- Put test helpers above than test vars
* Update checks in node pool tests
* Fix node pool check match