Evolve demo provider based on FastAPI

[dciangot]

Short Description of the issue

Use a mock provider that is based on:
https://github.com/interTwin-eu/interLink/blob/main/example/provider_demo.py

The objective is to include it into the CI/CD pipeline to make sure that FastAPI/OpenAPI/Interlink APIs are always aligned and working.

Environment

• Operating System:
• Other related components versions:

Steps to reproduce

Logs, stacktrace, or other symptoms

output

Summary of proposed changes