Provision default dockerimage for command-line-terminal.

[sleshchenko]

What does this PR do?

The main purpose of this PR is making controller provision default dockerimage for command-line-terminal.

As a second commit, it also makes endpoint health check compatible with OpenShift OAuth Routing:

1. Do not check TLS.
2. Consider 401 or 403 as successful response from endpoint.

What issues does this PR fix or reference?

N/A

Known limitations

1. Default dockerimage won't be applied if command line terminal is configured with reference.
   I tried to provision default dockerimage in component_controller.go where all plugins info is fetched but and dockerimage is successfully provisioned in workspace pod but no component is created.
   BTW This issue could be handled separately and this PR should contains enough to get rid of dockerimage component configuration on OpenShift Console.

Is it tested? How?

1. Create a command-line terminal workspace without dockerimage:

cat << EOF | oc apply -f - 
# It's just an example of workspace configuration OpenShift Console creates
# when user requests terminal
apiVersion: workspace.che.eclipse.org/v1alpha1
kind: Workspace
metadata:
  name: command-line-terminal
spec:
  started: true
  devfile:
    apiVersion: 1.0.0
    metadata:
      name: command-line-terminal
    components:
      - alias: command-line-terminal
        type: cheEditor
        id: che-incubator/command-line-terminal/4.5.0
EOF

2. Check that dockerimage component is created and workspace pod contains default openshift-plugin container.
3. Update default dockerimage used by controller

oc patch configmap che-workspace-controller --patch '{ "data": { "che.workspace.default_dockerimage.che-incubator.command-line-terminal": "alias: dev\nargs:\n- tail\n- -f\n- /dev/null\nenv:\n- name: PS1\n  value: \\[\\e[34m\\]>\\[\\e[m\\]\\[\\e[33m\\]>\\[\\e[m\\]\nimage: quay.io/eclipse/che-sidecar-openshift-connector:0.1.2-2601509\nmemoryLimit: 256Mi\ntype: dockerimage\n" } }' --type=merge
kc rollout restart deployment che-workspace-controller

3. Check that workspace is reconciled and dockerimage component is updated along with workspace pod.
4. Provision dockerimage into workspace spec

cat << EOF | oc apply -f - 
# It's just an example of workspace configuration OpenShift Console creates
# when user requests terminal
apiVersion: workspace.che.eclipse.org/v1alpha1
kind: Workspace
metadata:
  name: command-line-terminal
spec:
  started: true
  devfile:
    apiVersion: 1.0.0
    metadata:
      name: command-line-terminal
    components:
      - alias: command-line-terminal
        type: cheEditor
        id: che-incubator/command-line-terminal/4.5.0
      - type: dockerimage
        memoryLimit: 256Mi
        alias: dev
        image: 'quay.io/eclipse/che-sidecar-openshift-connector:0.1.2-2601509'
        args: ["tail", "-f", "/dev/null"]
        env:
          - value: 'hello'
            name: PS1
EOF

5. Verify that new env var came to dockerimage component + workspace pod.

[amisevsk]

LGTM.