feat: SQLite integration

[kayra1]

Description

This change brings CRUD and DB connection and disconnection functions for SQLite as well as simple validators for CSR and Certificates that will go into this DB.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that validate the behaviour of the software
• I validated that new and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[kayra1]

I'm not sure about this linter. All of these missing errchecks are intended, especially the one in tests. Go also doesn't allow _ := func to explicitly ignore err returns.

We resolved to put ignore comments in the tests.

[ghislainbourgeois]

Great start! I have some concerns around the pointers vs value semantics in the design.

[ghislainbourgeois]

This looks good to me, and I agree with the other comments on validation.go.

[ghislainbourgeois]

LGTM