Extend `PostgresqlSqlLexer` to handle PG14 SQL-standard function body syntax

[Mark Paluch]

PG14 added a new syntax for creating SQL functions that we should support with PostgresqlSqlLexer

CREATE OR REPLACE FUNCTION asterisks(n int)
  RETURNS SETOF text
  LANGUAGE sql IMMUTABLE STRICT PARALLEL SAFE
BEGIN ATOMIC
SELECT repeat('*', g) FROM generate_series (1, n) g; -- <-- Note this semicolon
END;

Right now, PostgresqlSqlLexer.tokenize(…) identifies this above as two statements. See also:

• pgjdbc/pgjdbc#2506
• npgsql/npgsql#4445

[Mark Paluch]

/cc @toverdijk

[toverdijk]

It does seem quite complex - I guess also the sql body needs to be parsed completely as well in order to catch commented out ENDs and such. I'll give it a shot..