Consolidate Kuberentes installation under k8s module

GRIT users should be able to:

• Create a cluster (GKE or EKS), install the operator and create a runner, all in one main.tf.
• Bring their own cluster, install the operator and create a runner.
• Bring their own cluster with the operator already install, and create a runner.

Therefore GRIT should be structured something like this:

/modules
  /aws
    /runner
    ...
    /eks_cluster
  /google
    /runner
    ...
    /gke_cluster
  /gitlab
    ...
  /k8s
    /operator (installs the operator)
    /runner   (created runners with the CRD)

We need to delete these folders:

/modules
  /operator
  /helm

Success criteria is "I can create a main.tf in my test project which creates a GKE cluster, installs the operator, installs a runner and registers to my test project."