Port over to fastapi #519

[joshdimanteto]

This PR will close #519

Description

Enter a description of the changes here

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 #519

Notes

• In the models all the relationships fields so ONE to ONE , ONE to MANY and MANY to MANY are optional. This was done because the model are deeply nested and can cascade. When they cascade they use the id generated by the parent for the given field e.g. so if you can create jobs in Applications, the job object would have the application id. This is a complex when it comes to Investigation when there is 4 levels deep so investigation - dataset - data file etc. for this to work you have to create many custom models of existing entities. So it is more efficient to make them optional. The ATTRIBUTES can be optional or mandatory depending on the SQL schema.

• The NULL values have been removed from the returns on the endpoints, this is because in some of the get endpoints you can use DISTINCT should only shows certain fields. If the other fields are None pydantic would fill it in with None values. This make object large for no benefit.