chore: Add kind integration test, fixes #41

[dhirajsb]

Description

Added kind integration test to build-image-pr.yaml workflow. It creates a Kind cluster, deploys operator image built for the PR in the test cluster, and checks that it can create a model registry from sample model registry CR. Fixes #41

How Has This Been Tested?

Tested GH action locally using act.

Merge criteria:

• [X] The commits and have meaningful messages; the author will squash them after approval or will ask to merge with squash.
• [X] Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• [X] The developer has manually tested the changes and verified that the changes work