Create users and databases declaratively

[masa213f]

What

User creation, database creation and grant privileges accordingly are typical operations for MySQL.
We want to be able to do these operations declaratively.

How

Describe how to address the issue.

Checklist

• Finish implementation of the issue
• Test all functions
• Have enough logs to trace activities
• Notify developers of necessary actions

[uqix]

How about pre-creating a database called app which is quite convenient in microservice architecture, like cnpg.

[ymmt2005]

@uqix Thanks for the info.
@masa213f @d-kuro I think this feature is worth doing.