Return Types on Create and Insert Table

[bh2smith]

Following up on a comment in #114. This PR introduces a cool new dataclass from dict/json parsing tool.

Note that we could also replace all the manually implemented "from_dict" methods throughout this project.

The expected way to use this dataclass_json library is as a decorator, but it fails the linter. There is an open issue in their repo related to this: lidatong/dataclasses-json#198 (comment)

[RichardKeo]

The tests that are failing are likely unrelated to the changes introduced here; instead they are small changes we made to the backend to restore the date format to what it was before we made some other changes.

[waddahAldrobi]

This is great, thank you!
But just shared thoughts on consistency of data class name

[waddahAldrobi]

lgtm!

[hawkaa]

Sweet!