DorisSQL: add Doris Dialect

Comienza con el esqueleto planificado del PR 1 para el dialecto de Doris y la limpieza del AST de AUTO_INCREMENT; después, sigue el plan de implementación apilado hasta las cláusulas de CREATE TABLE y las sentencias de carga de Doris. Se considera terminado cuando estén cubiertos el AST específico de Doris, los campos de CreateTable, el soporte de Display y span, las pruebas positivas y de rechazo del parser, las aserciones del AST, el renderizado de ida y vuelta y los casos de escape de comentarios.

Doris SQL: Support Doris Dialect

Summary

Add Doris SQL dialect, covering the core Doris syntax needed to parse common Doris DDL and load statements.

Motivation

Apache Doris has SQL syntax that differs from the generic SQL dialect, especially around CREATE TABLE clauses, key models, partition/distribution definitions, table properties, and Doris-specific load statements. A dedicated DorisDialect would let users parse Doris SQL without weakening generic parser behavior.

Proposed Scope

• Add DorisDialect
• Support Doris CREATE TABLE clauses:
  • ENGINE = OLAP
  • DUPLICATE KEY, UNIQUE KEY, AGGREGATE KEY
  • table COMMENT
  • PARTITION BY RANGE/LIST
  • AUTO PARTITION
  • DISTRIBUTED BY HASH/RANDOM
  • BUCKETS / BUCKETS AUTO
  • PROPERTIES (...)
• Support Doris column options such as AUTO_INCREMENT
• Support Doris LOAD DATA INFILE
• Support Doris CREATE ROUTINE LOAD
• Preserve generic dialect behavior where Doris-only syntax should remain rejected

Parser / AST Changes

• Add Doris-specific AST structures for key model, partition, distribution, table properties, and load statements
• Extend CreateTable with optional Doris-specific fields
• Add Display support for canonical SQL rendering
• Add span support for newly introduced AST nodes where applicable

Tests

Add Doris parser tests covering:

• Positive Doris parsing cases
• Generic/ANSI rejection cases for Doris-only syntax
• AST structure assertions
• Round-trip canonical rendering
• Escaping behavior for table comments containing single quotes

Implementation Plan

This feature is delivered as a stacked PR series. Each PR builds on the previous one.

• PR 1: Doris dialect skeleton + AUTO_INCREMENT AST cleanup
• PR 2: CREATE TABLE column options
• PR 3: CREATE TABLE key model and distribution
• PR 4: CREATE TABLE partition clauses + ON UPDATE + double-quoted COMMENT
• PR 5: LOAD DATA INFILE
• PR 6: CREATE ROUTINE LOAD