Support for UNSIGNED BIGINT to not be treated as byte[]

UNSIGNED BIGINT is treated as a Kafka Connect Decimal type and a value of a byte[] that makes it difficult to consume. Most to the time UNSIGNED BIGINT fields are used as primary key ids in DB tables (unnecessarily).

The proposal is to include a config item to Debezium to treat it as a INT64 schema type rather than a Decimal. This would be the default as most use cases do not need the full precision of UNSIGNED BIGINT.