spark-operator Add support for pod templates

A basic demonstration how we can utilize Spark's pod templates support https://spark.apache.org/docs/latest/running-on-kubernetes.html#pod-template with spark-on-k8s-operator. Closes https://github.com/GoogleCloudPlatform/spark-on-k8s-operator/issues/1176

Jul 05 '21 18:07 dszakallas

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