Add end-to-end tests to a sample API

[gomete]

Is your feature request related to a problem? Please describe.

Tests are covering the internal structure of the code but not the features and the API functionality.

Describe the solution you'd like

Add end-to-end tests in C# using Microsoft.AspNetCore.Mvc.Testing that can run in the pipeline as any other unit test. Add sample API using the AspNetCore package so we can use Microsoft.AspNetCore.Mvc.Testing to test the HTTP calls and using actual mock files.

Describe alternatives you've considered

You can run e2e tests with any other framework like cypress, Karate, etc.

Additional context