Add HUB_COMPONENT_DIR implicit variable for deployment hooks

Today we do restrict location where deployment hooks can be found. User will want to interact with artefacts inside component directory. To do so, hubctl should deliver environment variables

* `HUB_COMPONENT_DIR` - absolute path to component directory
* `HUB_BASE_DIR` - absolute path to hubfile

This will allow user to write something like `pre-deployment` hook like
```bash
cat << EOF > "$HUB_COMPONENT_DIR/values-generated.yaml"
serviceAccount:
create: true
name: "$HUB_COMPONENT"
automountServiceAccountToken: true
annotations:
iam.gke.io/gcp-service-account: "$USER_GSA"
nodeSelector:
iam.gke.io/gke-metadata-server-enabled: "true"
kubernetes.io/os: "linux"
EOF
```

That will seed some additional configuration for helm