remove database backend #489

[joshdimanteto]

This PR will close #489

Description

Remove the database backend functionality from the DataGateway API. It includes significant changes such as deleting database-related files and functionality, updating tests to remove database dependencies, and modifying the configuration to align with the changes.

Testing Instructions

Add a set up instructions describing how the reviewer should test the code

• Review code
• Check GitHub Actions build
• If icatdb Generator Script Consistency Test CI job fails, is this because of a deliberate change made to the script to change generated data (which isn't actually a problem) or is here an underlying issue with the changes made?
• Review changes to test coverage
• Does this change mean a new patch, minor or major version should be made? If so, does one of the commit messages feature fix:, feat: or BREAKING CHANGE: so a release is automatically made via GitHub Actions upon merge?
• {more steps here}

Agile Board Tracking

Connect to #489

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notes

The icat models still use SQLAlchemy, this is going to be update in the pydantic V2 upgrade to use pydantic

[joshdimanteto]

This name should change. I have changed in #524 where i had to refactored the tests

[VKTB]

I think the changes look fine, I tried my best. I have not tested it locally as I don't have a working stack to point it it to so I just trust that it works as expected. Might be worth asking someone else to have a look too. Approving.

[patrick-austin]

Functionally I think it's OK (I can run the API and get results back).

There's a few whitespace changes I would make (as a result of strings being moved onto one line) and one or two possible code changes.

[patrick-austin]

As discussed over Teams, there are some instances where the models do not strictly represent the types/fields required by the API (for example required fields when POSTing or id when PATCHing).

However, given that further changes are in progress with the FastAPI refactor and the primary use case for the API is DataGateway's read operations, I'm happy that the use of Optional lets things work for now, and it doesn't matter so much that someone referring to the Swagger wouldn't know id is required for PATCH (as who's looking at the Swagger in the first place?)