psql: Refine lexing of BEGIN...END blocks in CREATE FUNCTION statements
Only track BEGIN...END blocks if they are in a CREATE [OR REPLACE]
{FUNCTION|PROCEDURE} statement. Ignore if in parentheses.
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Discussion: https://www.postgresql.org/message-id/
cee01d26fe55bc086b3bcf10bfe4e8d450e2f608.camel@cybertec.at