Fix: disable persistent home when ephemeral storage used; persistent home volume shouldn't use capital letters

[AObuchow]

What does this PR do?

This PR makes 2 fixes to the $HOME persistence feature in DWO:

• The persistent home devfile volume is now only added if the DWOC's workspace.persistUserHome.enabled: true field is set, and the workspace requires persistent storage (i.e. it uses the uses async, per-workspace or per-user storage strategy and has at least one-non ephemeral volume or has mount-sources enabled).
• The persistent home volume name was changed from persistentHome -> persistent-home to be a valid Kubernetes name.

(Sorry for putting 2 bug fixes in a single PR - it seemed to make sense since they're both related)

What issues does this PR fix or reference?

1200 & #1203

Is it tested? How?

Initial setup

1. Set the $DWO_IMG environment variable to point to your quay repository for DWO, e.g: export DWO_IMG=quay.io/<your-username>/devworkspace-controller:next
2. Run make install_cert_manager docker install if testing on Minikube. For openshift, run make docker install
3. Enable persistUserHome in the DWOC: kubectl edit dwoc -n $NAMESPACE

apiVersion: controller.devfile.io/v1alpha1                                                                                                                                 
config:                                                                                                                                                                    
  routing:                                                                                                                                                                 
    clusterHostSuffix: 192.168.49.2.nip.io                                                                                                                                 
    defaultRoutingClass: basic                                                                                                                                             
  workspace:                                                                                                                                                               
    imagePullPolicy: Always                                                                                                                                                
+    persistUserHome:                                                                                                                                                       
+      enabled: true                                                                                                                                                        
kind: DevWorkspaceOperatorConfig

Testing fix for #1200

1. Create a devworkspace that uses persistent storage. The plain-devworkspace sample will suffice: kubectl apply -f ./samples/plain.yaml
2. Ensure the workspace starts up successfully with kubectl get dw -n $NAMESPACE -w
3. Check the workspace pod's spec, and verify it has a volumeMount with a subPath set to /persistent-home. For example:

(...)
        volumeMounts:                                                                                                                                                                                                                                                                            
        - mountPath: /home/user/                                                                                                                                           
          name: claim-devworkspace                                                                                                                                         
          subPath: workspace1835a0b4d9f04fd2/persistent-home   
(...)

Testing fix for #1203

1. Create a devworkspace that uses ephemeral storage. The following devworkspace can be used:

kind: DevWorkspace
apiVersion: workspace.devfile.io/v1alpha2
metadata:
  name: plain-devworkspace-ephemeral
spec:
  started: true
  routingClass: 'basic'
  template:
    attributes:
        controller.devfile.io/storage-type: ephemeral
    components:
      - name: web-terminal
        container:
          image: quay.io/wto/web-terminal-tooling:next
          memoryRequest: 256Mi
          memoryLimit: 512Mi
          mountSources: true
          command:
           - "tail"
           - "-f"
           - "/dev/null"

2. Ensure the workspace starts up successfully with kubectl get dw -n $NAMESPACE -w

$ kubectl get dw -n $NAMESPACE -w
NAME                           DEVWORKSPACE ID             PHASE     INFO
plain-devworkspace-ephemeral   workspace03197f210f9247e4   Running   Workspace is running

PR Checklist

• [ ] E2E tests pass (when PR is ready, comment /test v8-devworkspace-operator-e2e, v8-che-happy-path to trigger)
  • [ ] v8-devworkspace-operator-e2e: DevWorkspace e2e test
  • [ ] v8-che-happy-path: Happy path for verification integration with Che

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (093bb40) 52.82% compared to head (4d83873) 52.84%.

Files	Patch %	Lines
controllers/workspace/devworkspace_controller.go	0.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1210 +/- ## ========================================== + Coverage 52.82% 52.84% +0.01% ========================================== Files 84 84 Lines 7604 7604 ========================================== + Hits 4017 4018 +1 + Misses 3300 3299 -1 Partials 287 287 ```

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[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: amisevsk, AObuchow

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