[Auth] add healthcheck endpoint

[jbygdell]

Please describe the feature

As a operations team member, I want health checks for all my deployed applications so that I get a heads up when things are not working properly.

Acceptance criteria

• a /health or /ready endpoint exists that does the following:
  • calls the NSS server to ensure it is responding (if configured)
  • calls the OIDC server to ensure it is responding (if configured)
• Tests verifying the changes are added

Additional context

Estimation of size

small

Estimation of priority

medium