Join TABLE_CONSTRAINTS for check constraints since MySQL's CHECK_CONSTRAINTS table has no TABLE_NAME column

[sulimanbenhalim]

the database-schema tool returns empty check_constraints for every table on MySQL. MySQL's information_schema.CHECK_CONSTRAINTS has no TABLE_NAME column (MariaDB's does), so AND TABLE_NAME = ? throws Unknown column, the catch swallows it, and every table reports zero constraints.

fix joins information_schema.TABLE_CONSTRAINTS to map each constraint to its table, filtered to CONSTRAINT_TYPE = CHECK. works on both engines.

checked on real servers: mysql:8.0.46 goes from [] to the actual constraints for that table (and only that table), mariadb:11 returns the same rows before and after.

re-file of #968, reviewed and re-tested individually.