✨ auto alter table key definition

[kkharji]

Purpose

I'm trying to support more then just key definition but it seems to be an impossible task.

I'm thinking of later supporting versioning schema and definition migration strategy interface. Should open an issue for that

TODOs

• if default is present then replace null with default
• add more tests, in particular changing a key definition to include a reference to another table
• fix docgen remove of insert and schema docs
• keep foreign_keys off when it's already off and none of the keys has reference key