Integration tests

[daghovland]

Aim of the PR

This PR fixes AB#223357

Integration tests on the C# backend of the dexpi poc

Implementation

WebApplicationFactory for running the backend in tests. Dotnet TestContainers for runing Rdfox. Some tests of package and boundaries.

Type of change

• Bug fix
• New feature
• Breaking change
• This change requires a documentation update

If the changes impact any dependent services then provide details.

How Has This Been Tested?

Ran the tests locally

Additional Changes

The RdfoxApi was made non-static and included as a service. Upgraded to dotnet 9.

[markus-ap]

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[eoye]

Nice work! I did some minor cleanup, and also fixed the test in DatalogCreatorTests by removing whitespaces so the test doesn't fail due to different spaces and newlines. I also removed the unused Tests project.