Keycloak-config-cli should work with future versions of Keycloak server

[bohmber]

Problem Statement

Enabling ignoring unknown properties will make it easier for keycloak-config-cli to continue working with future Keycloak server versions.

Proposed Solution

Register an ObjectMapper with:

objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

in KeycloakProvider

Environment

• Keycloak Version: [e.g. 26.1.0]
• keycloak-config-cli Version: [e.g. 6.2.1]
• Java Version: [e.g. 21]

Additional information

No response

Acceptance Criteria

Keycloak-config-cli can work against a higher Keycloak version if no new feature is needed.