[lake/iceberg] Support ADD COLUMN schema evolution for Iceberg lake catalog

[fresh-borzoni]

Purpose

Linked issue: close #2592

Iceberg counterpart of #2128 / PR #2189 (Paimon). Sub-task of #2067.

IcebergLakeCatalog.alterTable() throws UnsupportedOperationException on schema changes.
This PR adds ADD COLUMN support for Iceberg-enabled tables.

Brief change log

• IcebergLakeCatalog: Implement AddColumn handling via Iceberg's UpdateSchema API (addColumn + moveBefore(__bucket))
• IcebergLakeCatalog: 3-way schema compatibility check for crash recovery idempotency (matching Paimon's pattern)
• IcebergLakeCatalog: normalize schemas to compare
• IcebergLakeCatalogTest: 7 new unit tests (happy path, error cases, idempotency, complex types)
• IcebergSchemaEvolutionITCase: 3 new e2e integration tests (log table, PK table, complex types)

[fresh-borzoni]

@luoyuxia @loserwang1024 @buvb
PTAL 🙏

[MehulBatra]

Thanks for raising the PR @fresh-borzoni , it's well-needed today, to make fluss-iceberg production ready, will take a look & review it!