Add health endpoint

**Is your feature request related to a problem? Please describe.**
Add a health endpoint at `/health` that returns 200 response with the following

**Describe the solution you'd like**
- [ ] add a test to verify `/health` endpoint exists (this will fail)
- [ ] add the `/health` endpoint
- [ ] add a test to verify the `/health` endpoint returns 200 with ` state = {"status": "UP"}` json response

**Describe alternatives you've considered**
N/A

**Additional context**
N/A