Adds a modifier function to simplify addition of local volumes to containerop

[swiftdiaries]

The normal method of adding volumes to containerop involves 3 steps

1. Define Volume using k8s python client
2. Create step using containerop
3. Add volume / volume mount to containerop

Like this:

# Define volume using the k8s python client
from kubernetes import client as k8s_client
pvc = k8s_client.V1PersistentVolumeClaimVolumeSource(claim_name='claim')
volume = k8s_client.V1Volume(name='workflow', persistent_volume_claim=pvc)
volume_mount = k8s_client.V1VolumeMount(mount_path='/mnt/workflow/',name='workflow')

# Create container_op
def step_op(mount_path, step_name='confusion_matrix'):
    return dsl.ContainerOp(
        name = step_name,
        image = 'image_name:image_tag',
        arguments = [
            'arg1', arg_1,
        ]
    )
step_name = step_op('/mnt/workflow')

# Add to containerop
step_name.add_volume(volume)
step_name.add_volume_mount(volume_mount)

This is fairly verbose.

With this change, we can add volumes from the DSL and we don't have to interact with the k8s client.
Syntax now:

1. Create step using containerop
2. Create volume with DSL
3. Add volume to step using DSL modifier function

# Create container_op
def step_op(mount_path, step_name='confusion_matrix'):
    return dsl.ContainerOp(
        name = step_name,
        image = 'image_name:image_tag',
        arguments = [
            'arg1', arg_1,
        ]
    )
step_name = step_op('/mnt/workflow')

# Volume definition
import kfp.onprem as onprem
local_volume = onprem.use_local_volume('claim', 'workflow', '/mnt/workflow')

# Add to step using modifier
step_name.apply(local_volume)

This is much more readable and enables better reuse of volumes across different steps.

---

This change is 

[swiftdiaries]

/cc @ramdootp

[swiftdiaries]

/assign @Ark-kun

[vicaire]

@swiftdiaries, what do you think of the proposal at #801?

[Ark-kun]

/lgtm

[Ark-kun]

/lgtm

[Ark-kun]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Ark-kun

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Ark-kun

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• sdk/OWNERS [Ark-kun]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[swiftdiaries]

Thanks for the review @Ark-kun !