Add health endpoint

[Hayk Davtyan]

Is your feature request related to a problem? Please describe.
The proposed endpoint should return "OK" when the dependent application, Prometheus, is ready and running properly.

Describe the solution you'd like
Implement a new FastAPI route, for example, /health, and include all checks that we use in the main module, such as filesystem checks, Prometheus checks, etc.

Describe alternatives you've considered
N/A

Additional context
N/A