Add Sail provider for Spark Connect compatible engine

[davidlghellin]

Add new Sail provider for Spark Connect compatible engine

This PR adds a new apache-airflow-providers-sail provider package that integrates
Sail (a Rust-native Spark Connect compatible engine) with
Apache Airflow.

Sail enables existing PySpark code to run without the JVM, using the Spark Connect
protocol (sc://).

Ref: lakehq/sail#300

Components included:

• SailHook: Connection management supporting remote (sc://) and local embedded mode
• PySailOperator: Execute code on Sail (remote or local server)
• @task.pysail: Task decorator for defining tasks as Python functions
• Unit tests, system test with example DAG, and documentation

Dependencies:

• pysail>=0.5.0 (Apache 2.0)
• pyspark>=3.5.2 (Apache 2.0)
• grpcio-status>=1.59.0 (Apache 2.0)

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[boring-cyborg]

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