feat(trainer): Introduce LocalTrainerClient

[eoinfennessy]

What this PR does / why we need it:

This PR introduces LocalTrainerClient to the Python SDK. This client implements the same interface as the existing TrainerClient, and enables users to run training jobs in Docker containers, without requiring a Kubernetes cluster.

Old PR: kubeflow/trainer#2610

Accompanying PR adding example notebook: kubeflow/trainer#2658

Which issue(s) this PR fixes

Fixes #2

Checklist:

• Docs included if any changes are user facing

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[franciscojavierarceo]

@andreyvelich @szaher is this PR still relevant?

[kramaranya]

@andreyvelich @szaher is this PR still relevant?

Nope, @briangallagher is going to create a new one for both Docker and Podman implementations

[andreyvelich]

This PR is implemented in: #33
/close

[google-oss-prow]

@andreyvelich: Closed this PR.

In response to this:

This PR is implemented in: #33
/close

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