[WIP][iceberg] Support the v3 variant type with row lineage and REST catalog

[plusplusjiajia]

Purpose

Add Iceberg v3 variant type support to Paimon's Iceberg compatibility layer, with the row lineage and REST catalog upgrade it requires. The three are interdependent: v3 variant metadata without row lineage is spec-invalid (Iceberg 1.10+ won't parse metadata lacking next-row-id/first-row-id), and row lineage without the REST upgrade still leaves rest-catalog storage creating v2 tables that reject v3 features.

• Variant type: IcebergDataField maps Paimon VARIANT ↔ Iceberg "variant" both ways. Before a snapshot is published, IcebergCommitCallback rejects types that cannot produce readable metadata: variant when format-version < 3 (and as a partition key, unconditionally), and nanosecond timestamps on every version (Paimon writes them as Parquet INT96, which Iceberg cannot read as timestamp_ns). Validation runs before publish and before a tag is written.
• Row lineage: IcebergManifestFileMeta/IcebergDataFileMeta gain first_row_id; ranges are assigned when writing the manifest list, mirroring Iceberg's ManifestListWriter. Tables upgraded from v2 get their surviving manifests assigned on the first v3 commit; regeneration continues past the highest published id so ids are never reused; rewritten/merged manifests keep unchanged rows' _row_id.
• REST upgrade: bump to Iceberg 1.10.1 (1.8.1 can't parse variant). Creation passes the configured format-version; a populated table whose version differs is dropped and recreated. Fallout: Hadoop 3.3.6 for FileSystem.openFile, jetty/commons-lang3 test-classpath alignment, RemoveSnapshot → RemoveSnapshots.