[Kubernetes][Cluster API Provider GCP] Improve CAPG by adding more features and support GKE

[nate-double-u]

CAPG is a subporject under the SIG-Cluster-LifeCycle and it is an implementation for GCP of Cluster-API which is a Kubernetes sub-project focused on providing declarative APIs and tooling to simplify provisioning, upgrading, and operating multiple Kubernetes clusters.

Mentor(s): Carlos Panato (@cpanato), Davanum Srinivas (@dims)

https://github.com/cncf/mentoring/blob/main/summerofcode/2022.md#improve-capg-by-adding-more-features-and-support-gke