[FLINK-40557][table] Make operation column optional in TO_CHANGELOG…

[ferenc-csaky]

What is the purpose of the change

Makes the operation column in TO_CHANGELOG optional. This supports append-only output that retains the input schema without prepending an operation code.

The change remains compatible with compiled plans created before the new argument was introduced.

Brief change log

• Adds optional include_op_column argument to TO_CHANGELOG, defaulting to true.
• Omits the operation column from inferred and runtime output when set to false.
• Preserves compatibility with existing compiled plans by defaulting a missing argument to true and supporting the previous eval signature.
• Adds type-inference and semantic test coverage.
• Documents the new argument in SQL documentation and Table API JavaDocs.

Verifying this change

This change added tests and was verified with:

• mvn -pl flink-table/flink-table-common -Dtest=ToChangelogOutputTypeStrategyTest test
• mvn -pl flink-table/flink-table-planner -Dtest=ToChangelogSemanticTests test
• mvn -pl flink-table/flink-table-planner -Dtest=ToChangelogRestoreTest test
• mvn spotless:check -pl flink-table/flink-table-common,flink-table/flink-table-runtime,flink-table/flink-table-api-java,flink-table/flink-table-planner

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): yes, adds a user-facing TO_CHANGELOG argument
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? docs + JavaDocs

Was generative AI tooling used to co-author this PR?

• Yes

Generated-by: OpenCode (openai/gpt-5.6-terra)

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CI report:

• 02b77a5 Azure: SUCCESS

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