WIP: 37 automated testing

[juakotorres]

In this MR I will start working with widget and integration tests. For now, I added the integrations test to try how they work. I added the official library for integration testing -> https://github.com/flutter/flutter/tree/main/packages/integration_test.

The idea of this MR is to add basic tests and check at least the base FHIR questionnaire resource. We are using the example project to be able to do integration testing.

I will be using my free time on this, so it will take time to implement 🙇 .

References from Flutter:

• Integration Testing -> https://docs.flutter.dev/cookbook/testing/integration/introduction
• Widget Testing -> https://docs.flutter.dev/cookbook/testing/widget/introduction
• Maybe we want to consider performance testing -> https://docs.flutter.dev/cookbook/testing/integration/profiling
• Debugging tools -> https://docs.flutter.dev/testing/debugging
• Tap, Drag and enter -> https://docs.flutter.dev/cookbook/testing/widget/tap-drag