Support `INSERT INTO table DEFAULT VALUES` in SQL triggers

[TarantoolBot]

SQL triggers now support the INSERT INTO table DEFAULT VALUES statement.
Note that this is primarily a parser change, as prior to this patch,
it was possible to insert default values into all but one column
by inserting into a single column, for example:

CREATE TABLE t1(i INT PRIMARY KEY);
CREATE TABLE t2(i INT PRIMARY KEY AUTOINCREMENT, a INT DEFAULT 1,
                b INT DEFAULT 2, c INT DEFAULT 3);
CREATE TRIGGER t1t AFTER INSERT ON t1 FOR EACH ROW BEGIN
    INSERT INTO t2(i) VALUES (NULL); END;

Requested by @ImeevMA in tarantool/tarantool@62cb643.