Provides a method to take our rules and configure them inside of GKE

• Template script will convert the file into a PrometheusRules object
  • Uses the filename to name the rule
  • reads in the yaml file and templates it into the Kuberenetes Object
  • Drops this into a new file which will only be loaded to validate it's proper yaml
  • We perform two checks as part of CI to validate the file MAY be okay:
    • validate yaml is legit yaml
    • We ensure that the rules are created using strings
  • We may still run into future situations where rules may contain invalid objects as we won't know failures until we watch the logs of the prometheus operator
• Applies a set of default labels for the rule selector to utilize: https://github.com/coreos/prometheus-operator/issues/2665#issuecomment-508941389
• To deploy, we'll rely on the Environments feature of GitLab and use a CI/CD pipeline to apply to the correct environment
  • Requires ops to be configured with the following ENV variables for each Environment we would deploy too:
    • PROJECT
    • REGION
    • CLUSTER
    • SERVICE_KEY
  • We use a simple for loop to iterate over the generated files to push them into kubernetes
• Modifies a few rules where validation indicated we need strings instead of floats or ints
• Since we need kubectl to apply these configurations, updates the Docker image to include the installation of said tool

Closes: https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/7180