Add Upgrade testing workflow

[DharmitD]

The issue resolved by this Pull Request:

Resolves #216

Description of your changes:

• This GH workflow sets up a kind cluster, installs OLM, deploys the OpenDataHub operator, deploys DSPO using a KfDef pointing to the most recently released branch specified via the GH action input. It further spins up a DSPA instance.
• The action upgrades DSPO to point to a candidate version, specified in the action input, and spins up a DSPA instance in a separate namespace.
• For now, we've set the most recently released branch to be an input just to be able to run and test this workflow out once merged, but we'll eventually set it to be the main branch of opendatahub/data-science-pipelines-operator repository in the KfDef.
• Specific upgrade testing checks to ensure that the upgrade went smoothly will be covered in a separate PR.

Testing instructions

Find a successful workflow run on my fork of the DSPO respository with this same set of configs here, tested out the workflow run multiple times to ensure there aren't any flaky successes:
https://github.com/DharmitD/data-science-pipelines-operator/actions/workflows/upgrade-test.yml

Checklist

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[DharmitD]

Latest successful run on my fork with these changes: https://github.com/DharmitD/data-science-pipelines-operator/actions/runs/6113169351/job/16592134955

[HumairAK]

/lgtm
/approve

[openshift-ci]

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