HttpClient wrapper for Keycloak API
Note
Keycloak Admin REST API has an OpenAPI definition (https://www.keycloak.org/docs-api/latest/rest-api/openapi.json), but it is still not perfect (e.g. operation IDs are missing), so automatic code generation is not feasible at the moment. keycloak/keycloak#8898 Once this PR (keycloak/keycloak#39011) is merged, it is worth to check code generation e.g. NSwag.