[SPARK-52297] Add Swift-based SparkPi K8s Job example

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR aims to add Swift-based SparkPi K8s Job example.

Why are the changes needed?

To provide a working example with

• Apache Spark 4.0.0 Connect Server launched by Apache Spark Kubernetes Operator 0.2.0 Helm chart.
• SparkPi Swift App developed with Apache Spark Connect for Swift 0.2.0 library.
• Swift 6.1 language

Does this PR introduce any user-facing change?

No behavior change because this is a new example.

How was this patch tested?

Manual tests.

# Install Spark K8s Operator
$ helm install spark spark/spark-kubernetes-operator

# Launch Spark 4.0 Connect Server
$ kubectl apply -f examples/spark-connect-server.yaml

# Launch `Swift-based SparkPi` Application
$ kubectl  apply -f examples/job/pi-swift.yaml

# Check the log
$ kubectl logs -f job/spark-connect-swift-pi
Pi is roughly 3.142923142923143

Was this patch authored or co-authored using generative AI tooling?

No.

[dongjoon-hyun]

When spark-connect-swift gets the repository, this will be replaced with the official one.

• https://issues.apache.org/jira/browse/INFRA-26846

[dongjoon-hyun]

cc @viirya , @peter-toth , @jiangxb1987

[dongjoon-hyun]

Thank you so much, @viirya !
Merged to main.