if a Volume is defined by the operator don't add another "work" volume. (#1015)

This allows providing a different `work` Volume.

This should be a cloud agnostic way of allowing the operator to use (for example) NVME backed storage.

This is a working example where the workDir will use the provided volume, additionally here docker is placed on the same NVME.
```
apiVersion: actions.summerwind.dev/v1alpha1
kind: RunnerDeployment
metadata:
  name: runner-2
spec:
  template:
    spec:
      dockerdContainerResources: {}
      env:
      - name: POD_NAME
        valueFrom:
          fieldRef:
            fieldPath: metadata.name
      # this is to mount the docker in docker onto NVME disk
      dockerVolumeMounts:
      - mountPath: /var/lib/docker
        name: scratch
        subPathExpr: $(POD_NAME)-docker
      - mountPath: /runner/_work
        name: work
        subPathExpr: $(POD_NAME)-work
      volumeMounts:
      - mountPath: /runner/_work
        name: work
        subPathExpr: $(POD_NAME)-work
      dockerEnv:
      - name: POD_NAME
        valueFrom:
          fieldRef:
            fieldPath: metadata.name
      volumes:
      - hostPath:
          path: /mnt/disks/ssd0
        name: scratch
      - hostPath:
          path: /mnt/disks/ssd0
        name: work
      nodeSelector:
       cloud.google.com/gke-nodepool: runner-16-with-nvme
      ephemeral: false
      image: ""
      imagePullPolicy: Always
      labels:
        - runner-2
        - self-hosted
      organization: yourorganization

```

controllers/runner_controller.go

@@ -672,10 +672,29 @@ func (r *RunnerReconciler) newPod(runner v1alpha1.Runner) (corev1.Pod, error) {
 	runnerSpec := runner.Spec
 
 	if len(runnerSpec.VolumeMounts) != 0 {
+		// if operater provides a work volume mount, use that
+		isPresent, _ := workVolumeMountPresent(runnerSpec.VolumeMounts)
+		if isPresent {
+			// remove work volume since it will be provided from runnerSpec.Volumes
+			// if we don't remove it here we would get a duplicate key error, i.e. two volumes named work
+			_, index := workVolumeMountPresent(pod.Spec.Containers[0].VolumeMounts)
+			pod.Spec.Containers[0].VolumeMounts = append(pod.Spec.Containers[0].VolumeMounts[:index], pod.Spec.Containers[0].VolumeMounts[index+1:]...)
+		}
+
 		pod.Spec.Containers[0].VolumeMounts = append(pod.Spec.Containers[0].VolumeMounts, runnerSpec.VolumeMounts...)
 	}
 
 	if len(runnerSpec.Volumes) != 0 {
+		// if operator provides a work volume. use that
+		isPresent, _ := workVolumePresent(runnerSpec.Volumes)
+		if isPresent {
+			_, index := workVolumePresent(pod.Spec.Volumes)
+
+			// remove work volume since it will be provided from runnerSpec.Volumes
+			// if we don't remove it here we would get a duplicate key error, i.e. two volumes named work
+			pod.Spec.Volumes = append(pod.Spec.Volumes[:index], pod.Spec.Volumes[index+1:]...)
+		}
+
 		pod.Spec.Volumes = append(pod.Spec.Volumes, runnerSpec.Volumes...)
 	}
 	if len(runnerSpec.InitContainers) != 0 {
@@ -991,6 +1010,7 @@ func newRunnerPod(template corev1.Pod, runnerSpec v1alpha1.RunnerConfig, default
 				},
 			},
 		)
+
 		runnerContainer.VolumeMounts = append(runnerContainer.VolumeMounts,
 			corev1.VolumeMount{
 				Name:      "work",
@@ -1002,6 +1022,7 @@ func newRunnerPod(template corev1.Pod, runnerSpec v1alpha1.RunnerConfig, default
 				ReadOnly:  true,
 			},
 		)
+
 		runnerContainer.Env = append(runnerContainer.Env, []corev1.EnvVar{
 			{
 				Name:  "DOCKER_HOST",
@@ -1020,10 +1041,6 @@ func newRunnerPod(template corev1.Pod, runnerSpec v1alpha1.RunnerConfig, default
 		// Determine the volume mounts assigned to the docker sidecar. In case extra mounts are included in the RunnerSpec, append them to the standard
 		// set of mounts. See https://github.com/actions-runner-controller/actions-runner-controller/issues/435 for context.
 		dockerVolumeMounts := []corev1.VolumeMount{
-			{
-				Name:      "work",
-				MountPath: workDir,
-			},
 			{
 				Name:      runnerVolumeName,
 				MountPath: runnerVolumeMountPath,
@@ -1034,6 +1051,14 @@ func newRunnerPod(template corev1.Pod, runnerSpec v1alpha1.RunnerConfig, default
 			},
 		}
 
+		mountPresent, _ := workVolumeMountPresent(dockerdContainer.VolumeMounts)
+		if !mountPresent {
+			dockerVolumeMounts = append(dockerVolumeMounts, corev1.VolumeMount{
+				Name:      "work",
+				MountPath: workDir,
+			})
+		}
+
 		if dockerdContainer.Image == "" {
 			dockerdContainer.Image = defaultDockerImage
 		}
@@ -1139,3 +1164,21 @@ func removeFinalizer(finalizers []string, finalizerName string) ([]string, bool)
 
 	return result, removed
 }
+
+func workVolumePresent(items []corev1.Volume) (bool, int) {
+	for index, item := range items {
+		if item.Name == "work" {
+			return true, index
+		}
+	}
+	return false, 0
+}
+
+func workVolumeMountPresent(items []corev1.VolumeMount) (bool, int) {
+	for index, item := range items {
+		if item.Name == "work" {
+			return true, index
+		}
+	}
+	return false, 0
+}