Override the runner pod spec

Both TerraformRepository and TerraformLayer expose a spec.overrideRunnerSpec map field.

If the field is specified for a given TerraformRepository it will be applied by default to all TerraformLayer linked to it.

If the field is specified for a given TerraformLayer it will take precedence over the TerraformRepository configuration.

Available overrides are:

Fields
ImagePullSecrets
Image
Tolerations
NodeSelector
ServiceAccountName
Resources
Env
EnvFrom
Volumes
VolumeMounts
Metadata.Annotations
Metadata.Labels

For instance with the following configuration, all the runner pods will have the specifications described inside the TerraformRepository:

apiVersion: config.terraform.padok.cloud/v1alpha1
kind: TerraformRepository
metadata:
  name: burrito
  namespace: burrito
spec:
  repository:
    url: https://github.com/padok-team/burrito
  overrideRunnerSpec:
    imagePullSecrets:
    - name: ghcr-creds
    tolerations:
    - effect: NoSchedule
      key: burrito.io/production
      operator: Exists
    nodeSelector:
      production: "true"
    serviceAccountName: "production"
---
apiVersion: config.terraform.padok.cloud/v1alpha1
kind: TerraformLayer
metadata:
  name: random-pets
  namespace: burrito
spec:
  terraform:
    version: "1.3.1"
  path: "internal/e2e/testdata/random-pets"
  branch: "main"
  repository:
    name: burrito
    namespace: burrito

In the following case, tolerations and nodeSelector will be merged:

apiVersion: config.terraform.padok.cloud/v1alpha1
kind: TerraformRepository
metadata:
  name: burrito
  namespace: burrito
spec:
  repository:
    url: https://github.com/padok-team/burrito
  overridePodSpec:
    imagePullSecrets:
    - name: ghcr-creds
    tolerations:
    - effect: NoExecute
      key: burrito.io/production
      operator: Exists
    nodeSelector:
      production: "true"
    serviceAccountName: "production"
---
apiVersion: config.terraform.padok.cloud/v1alpha1
kind: TerraformLayer
metadata:
  name: random-pets
  namespace: burrito
spec:
  terraform:
    version: "1.3.1"
  path: "internal/e2e/testdata/random-pets"
  branch: "main"
  repository:
    name: burrito
    namespace: burrito
  overrideRunnerSpec:
    tolerations:
    - effect: NoSchedule
      key: burrito.io/production
      operator: Exists
    nodeSelector: {}

Resulting in the following podSpec:

tolerations:
- effect: NoSchedule
  key: burrito.io/production
  operator: Exists
nodeSelector:
  production: "true"