Add GitHub action workflow for publishing latest spark-operator and kubectl images

[ChenYi015]

Purpose of this PR

Proposed changes:

• Add a new GitHub action workflow for publishing latest spark-operator and kubectl images.

Change Category

• Bugfix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that could affect existing functionality)
• Documentation update

Rationale

Checklist

• I have conducted a self-review of my own code.
• I have updated documentation accordingly.
• I have added tests that prove my changes are effective or that my feature works.
• Existing unit tests pass locally with my changes.

Additional Notes

[google-oss-prow]

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[nabuskey]

LGTM