Add support for unsigned integer types

We already support the following sign integer types are signed:

• TINYINT -> INT16
• SMALLINT -> INT16
• MEDIUMINT -> INT32
• INT-> INT32
• BIGINT -> INT64

We need to add support for their unsigned types:

• UNSIGNED TINYINT -> INT16
• UNSIGNED SMALLINT -> INT32
• UNSIGNED MEDIUMINT -> INT32
• UNSIGNED INT -> INT64
• UNSIGNED BIGINT -> INT64 (if overflow, max unsigned long `18446744073709551615` becomes -1, `18446744073709551614` becomes -2, etc), MySQL Connector has the same behavior.