Add in docs for deploying Hybrid Reference Architectures on GCP

Closes https://gitlab.com/gitlab-org/quality/gitlab-environment-toolkit/-/issues/89

MR adds in documentation on how to deploy Cloud Native Hybrid Reference Architectures with GET on a new page. This MR only covers GCP setups with others to follow.

Additionally MR updates the format of the main Ansible settings file to be clearer as it continues to grow. Mimics formatting of the gitlab.rb file.