support PARTITION syntax in CREATE TABLE

[zachmu]

Customers migrating from MySQL require this. We don't need to support the actual partition definitions at this point, just make them parse without error. Feature described here:

https://dev.mysql.com/doc/refman/8.0/en/partitioning-overview.html

Here's an example from a customer:

CREATE TABLE employees (
    id INT NOT NULL,
    fname VARCHAR(30),
    lname VARCHAR(30),
    hired DATE NOT NULL DEFAULT '1970-01-01',
    separated DATE NOT NULL DEFAULT '9999-12-31',
    job_code INT NOT NULL,
    store_id INT NOT NULL
)
PARTITION BY RANGE (store_id) (
    PARTITION p0 VALUES LESS THAN (6),
    PARTITION p1 VALUES LESS THAN (11),
    PARTITION p2 VALUES LESS THAN (16),
    PARTITION p3 VALUES LESS THAN (21)
);