Sqlitedb API implementation

[thorbjoernl]

Change Summary

Provides an initial implementation for storing json blobs in an sqlite database.

Related issue number

• closes Sqlite API #16,

• closes AerovalDB should support more than one db-format #52

Checklist

• Start with a draft-PR
• The PR title is a good summary of the changes
• PR is set to AeroTools and a tentative milestone
• Documentation reflects the changes where applicable
• Tests for the changes exist where applicable
• Tests pass locally
• Tests pass on CI
• At least 1 reviewer is selected
• Make PR ready to review

[heikoklein]

Congratulations, having two independent implementations is an important step for aerovaldb.

With this step you also refactored much of jsondb code and testing, which was expected, but is also a bit overwhelming when reading the PR. I would have prefered several smaller PRs, e.g. about the refactoring of jsondb, changes introduced in testing and then only sqlitedb. Now, it is impossilbe to see for me where a change is coming from and where it might eventually break functionality. But this just as a note for the future.

What is completely missing is the documention on 'How to implement add an additional aerovaldb implementation', similar to https://pyaro.readthedocs.io/en/latest/how-to-add-new-reader.html . With the addition of sqlitedb you made a lot of decisions about that, and that should be documented. Since the documentation isn't strictly necessary for this PR, I approve.

[thorbjoernl]

Thanks for reviewing :) I'll try to keep changes smaller and more manageable in the future.

I've created an issue for the documentation here for future reference: #80