Add support for ephemeral volumes.

[kadel]

Devfile 2.1.0 introduced new field in volume components called ephemeral

When ephemeral: true the volume should be always created as emptyDir

- name: volume-test
  volume:
    size: 1Gi
    ephemeral: true

/kind feature
/area devfile
/priority high

[kadel]

/status blocked
missing support for ephemeral in devfile/libary
devfile/api#642

[kadel]

devfile/api#642

fixed

/remove-status blocked

[valaparthvi]

odo has ephemeral setting, which when set to true, uses emptyDir{} for volume.
With the new volume.ephemeral field, if it is set to true, emptyDir{} should be used to create volumes.
Devfile should get a preference, so even if ephemeral is set to false, devfile should get a preference. The default value for volume.ephemeral is set to false.

We do not remove odo's ephemeral setting as of now because it is required for odo-project volume where we store the source code.

To reproduce this issue, create a java-maven component, change the apiVersion to 2.1.0 and add ephemeral: true to the m2 volume.
Mainly would require updating the [createOrUpdateComponent](https://github.com/openshift/odo/blob/main/pkg/devfile/adapters/kubernetes/component/adapter.go#L427) method.

Acceptance Criteria:

• if volume.ephemeral is set to true; create an emptyDir{} volume
• if volume.ephemeral is set to false(default); create PVC, it should work like it does now
• Integration test
• Unit test
• Add klog wherever necessary.

[feloy]

Do we want to add a flag --ephemeral=true/false to the odo storage create command as part of this PR?

[kadel]

Do we want to add a flag --ephemeral=true/false to the odo storage create command as part of this PR?

this is good idea 👍 . We should do that.