Feature: Import PostgreSQL 17 RC1 new parser.

Feature: Import PostgreSQL 17 RC1 new parser.

Major changes of PostgreSQL 17 parser include:

- Allow MERGE to use NOT MATCHED BY SOURCE and RETURNING clause:

    MERGE INTO ... WHEN NOT MATCHED BY SOURCE ...
    MERGE INTO ... RETURNING ...

- Add new COPY option ON_ERROR ignore and LOG_VERBOSITY:

  COPY ... WITH (ON_ERROR ignore);
  COPY ... WITH (LOG_VERBOSITY verbose);

- Allow to use '*' to specify the COPY FROM options FORCE_NOT_NULL and FORCE_NULL for all columns.

  COPY ... WITH (FORCE_NOT_NULL *);
  COPY ... WITH (FORCE_NULL *);

- Add EXPLAIN option SERIALIZE and MEMORY

  EXPLAIN (MEMORY) ...
  EXPLAIN (ANALYZE, SERIALIZE ...) ...

- Allow ALTER TABLE to use SET STATISTICS DEFAULT to set a column to the default statistics target

  ALTER TABLE ... ALTER COLUMN ... SET STATISTICS DEFAULT;

- Allow ALTER TABLE to change a column's generation expression

  ALTER TABLE ... ALTER COLUMN ... SET EXPRESSION;

- Add DEFAULT setting for ALTER TABLE .. SET ACCESS METHOD

  ALTER TABLE ... SET STATISTICS DEFAULT;

- Allow event triggers to use login event:

  CREATE EVENT TRIGGER ... ON login ...

- Add event trigger support for REINDEX.