feat: introduce Result Service using Lakekeeper as REST catalog for Iceberg - catalog migration

[mengw15]

What changes were proposed in this PR?

This is PR 1 of a decomposed series from #4242, focusing on the core Iceberg catalog migration to support Lakekeeper as a
REST catalog.

Scala changes:

• IcebergUtil.scala: added createRestCatalog() for REST catalog connections with S3FileIO (MinIO), and namespace auto-creation for all catalog types
• IcebergCatalogInstance.scala: updated singleton to support REST catalog type selection
• IcebergTableWriter.scala: updated for REST catalog compatibility
• StorageConfig.scala / EnvironmentalVariable.scala: added REST catalog configuration (URI, warehouse name, region, S3
  bucket) and environment variable support
• storage.conf: added REST catalog config section (default remains postgres for backward compatibility)
• build.sbt: added iceberg-aws, AWS SDK dependencies, and Netty version override for Arrow compatibility
• PythonWorkflowWorker.scala / ComputingUnitManagingResource.scala: propagate REST catalog config to Python workers and
  computing units

Python changes:

• iceberg_catalog_instance.py / iceberg_utils.py: added REST catalog support via PyIceberg
• storage_config.py: added REST catalog configuration parsing
• texera_run_python_worker.py: accept REST catalog config from Scala side
• requirements.txt: upgraded PyIceberg (0.8.1 → 0.9.0), added s3fs/aiobotocore for S3 access

Database:

• texera_lakekeeper.sql: schema for Lakekeeper's backing database

Note: This PR keeps postgres as the default catalog type in storage.conf. Switching to REST catalog will be enabled
in subsequent deployment PRs.

Any related issues, documentation, discussions?

Part of #4126. Subsequent PRs will cover:

• Lakekeeper bootstrap script
• Single-node deployment
• Kubernetes deployment
• CI integration

How was this PR tested?

Manual

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

co-authored with Claude