Add sparkVersion field to JobLaunchConf

[dushyantk1509]

Summary

• Adds sparkVersion field to JobLaunchConf to allow per-job Spark version configuration via jobs.yaml
• Enables gradual migration of maintenance jobs from Spark 3.1 to 3.5 without code changes. Starting with OFD - picks up stream-results option for remove orphan files (Spark: backport stream-results option for remove orphan files iceberg#234) to prevent driver OOM when removing large numbers of orphan files.

Changes

• Client-facing API Changes
• Internal API Changes
• Bug Fixes
• New Features
• Performance Improvements
• Code Style
• Refactoring
• Documentation
• Tests

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Testing Done

• Manually Tested on local docker setup. Please include commands ran, and their output.
• Added new tests for the changes made.
• Updated existing tests to reflect the changes made.
• No tests added or updated. Please explain why. If unsure, please feel free to ask for help.
• Some other form of testing like staging or soak time in production. Please explain.

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Additional Information

• Breaking Changes
• Deprecations
• Large PR broken into smaller PRs, and PR plan linked in the description.

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