AutoIncrement should convert to { INT | BIGINT } IDENTITY, instead of { SERIAL | BIGSERIAL }

[DJFarr]

Hi,

I've seen this issue posted on the internet a few times, and even one issue in the liquibase repo which as been open for years (liquibase/liquibase#3505).

As stated, an INT or BIGINT column set to AutoIncrement: true in redshift should actually generate an IDENTITY column, as its the alternative to SEQUENCES.

I have connected to a new redshift instance, and put the driver and this extension in my liquibase/lib/ folder, and when i run liquibase update-sql the generated SQL contains SERIALs.

Doc:
https://docs.aws.amazon.com/redshift/latest/dg/r_CREATE_TABLE_NEW.html
Examples:
https://docs.aws.amazon.com/redshift/latest/dg/r_CREATE_TABLE_examples.html

I felt like this was a better place for this issue to sit rather than the core repo.
I'm new to liquibase and this repo so I'm not confident enough yet to make my own PR.