Implement loadimage addon for GKE

[czeslavo]

Is there an existing issue for this?

• I have searched the existing issues

Problem Statement

When running tests against GKE, it would be handy if the loadimage.Addon could handle pushing images to Artifact Repository to make them available from the cluster.

Proposed Solution

• Extend the loadimage.Addon implementation to handle GKE cluster type (possibly by pushing the image to Artifact Repository)
• Add E2E test verifying that a locally built image after loading it with the addon is available from a GKE cluster

Additional information

No response

Acceptance Criteria

• When loadimage.Addon is deployed with a locally built image, the image is available from a GKE cluster in the same Google Cloud project