[lake/paimon] Prohibit users from setting Paimon properties that Fluss depends on

[LiebingYu]

Purpose

Linked issue: close #1824

Brief change log

Tests

API and Format

Documentation

[Copilot]

Pull Request Overview

This PR prevents users from manually setting Paimon options that Fluss manages, centralizing validation and conversion logic in PaimonConversions and adding tests to enforce the restriction.

• Add validation to block unsettable/default Paimon options and set sane defaults in PaimonConversions.
• Refactor schema and option conversion from PaimonLakeCatalog into PaimonConversions.
• Add an integration test asserting that attempts to set reserved Paimon options throw InvalidConfigException.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
fluss-lake/fluss-lake-paimon/src/main/java/org/apache/fluss/lake/paimon/utils/PaimonConversions.java	Introduces validation for unsettable Paimon options, default option handling, and consolidates conversion utilities.
fluss-lake/fluss-lake-paimon/src/main/java/org/apache/fluss/lake/paimon/PaimonLakeCatalog.java	Refactors to use PaimonConversions for identifier/schema/option conversions; removes duplicated logic.
fluss-lake/fluss-lake-paimon/src/test/java/org/apache/fluss/lake/paimon/LakeEnabledTableCreateITCase.java	Adds a test ensuring reserved Paimon options cannot be set by users.

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[Copilot]

PAIMON_DEFAULT_OPTIONS is an Options instance which does not expose keySet(); this will not compile. Use PAIMON_DEFAULT_OPTIONS.toMap().keySet() to obtain the keys.

Suggested change

	keys.addAll(PAIMON_DEFAULT_OPTIONS.keySet());
	keys.addAll(PAIMON_DEFAULT_OPTIONS.toMap().keySet());

[Copilot]

PaimonConversions now statically depends on PaimonLakeCatalog via SYSTEM_COLUMNS while PaimonLakeCatalog depends on PaimonConversions, creating tight coupling. Consider moving SYSTEM_COLUMNS to a dedicated constants/util class to avoid circular dependencies and improve modularity.

Suggested change

	import static org.apache.fluss.lake.paimon.PaimonLakeCatalog.SYSTEM_COLUMNS;
	import static org.apache.fluss.lake.paimon.PaimonLakeConstants.SYSTEM_COLUMNS;

[luoyuxia]

@LiebingYu Thanks for the pr. Left minor comments. PTAL

[luoyuxia]

+1