Ability to run as less privileged user

[clayrosenthal]

What would you like to be added

I want to run step ca as a less privileged user, who can only insert, update, and select from tables, without creating or destroying any tables or databases. The database and tables are only made on the first start, so after they don't need to be recreated. The current implementation here always runs CREATE IF NOT EXISTS rather than just checking existence. I would like to check the existence with a separate query like SHOW TABLES LIKE <X> before trying to create.

Why this is needed

To be able to run step-ca with a less privileged user for security purposes