Upgrade Keycloak to v16

• update helm chart
• Use Earthly to generate new Keycloak image with plugins.
• Upload image to this repo's container registry.
• Update image tag in chart/values.yaml
• fix any cypress test errors
• include custom plugin code changes
• test user auth flow - registration, and login. with and without CAC
• test end-to-end SSO for OIDC and SAML