Feat: Add Apache Doris engine adapter with OLAP and Iceberg multi-catalog support

[brucearctor]

Summary

Adds first-class Apache Doris (DorisEngineAdapter and DorisConnectionConfig) engine support to SQLMesh, including both native Doris OLAP tables (UNIQUE KEY Merge-on-Write, DUPLICATE KEY, AGGREGATE KEY) and Doris-backed Apache Iceberg multi-catalog tables (catalog.db.table / table_format = 'iceberg').

Closes #5875
Supersedes / builds upon #5033 (with Co-authored-by: xinge.ji <xinge.ji@outlook.com>)

Key Capabilities

• Connection & Session Management (DorisConnectionConfig):
  • Connects via PyMySQL (sqlmesh[doris]) with autocommit=True and automatic cursor reconnect on transient MySQL-protocol disconnects (OperationalError 2006 / 2013 / 2055) when outside a transaction.
  • Supports catalog, session_variables (e.g., workload_group, enable_unique_key_partial_update), ssl, and configurable connect_timeout / read_timeout / write_timeout.
  • Registered in FORBIDDEN_STATE_SYNC_ENGINES with a clear configuration error guiding users to configure a dedicated state_connection.
• Native Doris OLAP Table Models & Key Prefix Ordering:
  • Supports UNIQUE KEY (including INCREMENTAL_BY_UNIQUE_KEY auto-propagation, Merge-on-Write properties, and custom order_by sort keys), DUPLICATE KEY, and AGGREGATE KEY.
  • Automatically reorders OLAP key columns to the leading prefix of CREATE TABLE schemas and CTAS projections (_reorder_olap_columns) and ensures column index 0 is a valid Doris OLAP key type (never FLOAT, DOUBLE, ARRAY, MAP, STRUCT, JSON, or VARIANT).
• Doris DeleteHandler & Logical Merge Semantics:
  • Rewrites DELETE FROM ... WHERE col IN (SELECT ...) (and CONCAT_WS composite keys from LogicalMergeMixin) into Doris's DELETE FROM target AS _t1 USING (...) AS _t2 WHERE ... syntax for UNIQUE KEY tables.
  • Provides automatic fallback to cardinality-aware batched literal DELETE (_delete_by_literal_keys) for DUPLICATE KEY, AGGREGATE KEY, and Iceberg tables without emitting OR or BETWEEN predicates rejected by Doris's DeleteHandler.
• Partitioning (RANGE, LIST, Dynamic, AUTO PARTITION, and Iceberg Transforms):
  • Supports manual RANGE / LIST partitions, dynamic_partition.* properties, auto_partition (AUTO PARTITION BY RANGE (DATE_TRUNC(...)) ()), and Iceberg partition transforms (PARTITION BY LIST (day(ts), region) ()).
  • Extracts underlying base columns from partition transform expressions during insert_overwrite_by_partition.
• Materialized Views (Async MTMV & Sync Rollup MV):
  • Supports both asynchronous multi-table materialized views (BUILD IMMEDIATE|DEFERRED, REFRESH ... ON MANUAL|COMMIT|SCHEDULE) and synchronized single-table rollup materialized views (materialized_type = 'SYNC').
• Apache Iceberg & External Multi-Catalog (CatalogSupport.FULL_SUPPORT):
  • Supports 3-part catalog.db.table naming, SWITCH <catalog>, catalog-scoped information_schema.tables discovery, INSERT OVERWRITE TABLE for Iceberg full refresh, and safe view guards / environment_catalog_mapping support when targeting external catalogs.

Testing

• Unit & Invariant Tests: 52 unit and parametrized invariant tests in tests/core/engine_adapter/test_doris.py and tests/core/test_connection_config.py.
• Live Docker Integration Suite (apache/doris:fe-4.0.8 & apache/doris:be-4.0.8):
  • All shared engine integration tests in tests/core/engine_adapter/integration/test_integration.py (-m "doris", including test_sushi in full and dev_only modes, test_value_normalization, test_table_diff, test_alter_table, test_materialized_view, SCD Type 2, and incremental strategies) pass against Doris 4.0.8.
  • Doris-specific and local Iceberg multi-catalog integration tests in tests/core/engine_adapter/integration/test_integration_doris.py.