Support WITH expression

[apstndb]

WITH expression is not yet supported.

Syntax

https://cloud.google.com/spanner/docs/reference/standard-sql/operators#with_expression

WITH(variable_assignment[, ...], result_expression)

variable_assignment:
  variable_name AS expression

$ go run ./tools/parse --mode query 'SELECT WITH(s AS SUM(input), c AS COUNT(input), s/c) FROM UNNEST([1.0, 2.0, 3.0]) AS input;'
2024/10/04 01:34:52 syntax error::1:8: unexpected token: WITH

  1:  SELECT WITH(s AS SUM(input), c AS COUNT(input), s/c) FROM UNNEST([1.0, 2.0, 3.0]) AS input;
             ^~~~
exit status 1

Reference

In ZetaSQL

• https://github.com/google/zetasql/blob/194cd32b5d766d60e3ca442651d792c7fe54ea74/zetasql/parser/gen_parse_tree.py#L9811-L9826
• https://github.com/google/zetasql/blob/194cd32b5d766d60e3ca442651d792c7fe54ea74/zetasql/parser/bison_parser.y#L7680-L7704