ci: introduce spark paimon integration for integration test

[luoyuxia]

Purpose

Linked issue: close #108

Inspired by iceberg-rust apache/iceberg-rust#766, this pr only introduce base testing infra for reading, will add integration tests in follow pull requests.

Brief change log

• Add Docker Compose configuration for Spark + Paimon environment
• Add Makefile targets (docker-up, docker-down) for managing test containers
• Add Spark Dockerfile with configurable SPARK_VERSION and PAIMON_VERSION build args
• Add provision.py script to create test tables and data
• Add CI integration job to run Docker containers (with cleanup on completion)
• Use /tmp/paimon-warehouse as shared volume between Spark and host for test data

Tests

API and Format

Documentation

[luoyuxia]

cc @XiaoHongbo-Hope