Add Health Endpoint

[DiCanio]

A simple health endpoint for status checking is required. Especially for Docker and Kubernetes deployments where health checks can be leveraged.

[DiCanio]

Just leaving this here for future use:

• https://docs.spring.io/spring-boot/docs/current/reference/html/actuator.html#actuator.endpoints.exposing
• https://docs.spring.io/spring-boot/docs/current/reference/html/actuator.html#actuator.endpoints.health