Update Comet Starter App with Keycloak integration

[jbouder]

Is your feature request related to a problem? Please describe.
In order to provide a more complete starter app, this repo should be updated to include all baseline configurations for use with Keycloak as an auth provider.

Describe the solution you'd like

• Add keycloak configs and dependencies
• Update signin/signout to utilize keycloak auth
• Allow mocking keycloak auth for testing purposes

Describe alternatives you've considered
N/A

Additional context
N/A