Add option to univention-keycloak to set a client authentication flow. If None/empty string passed - reset to default (which is browser)
4ae9734348 | `univention-keycloak` implements an option to set client's authentication flow. f0b4272b93 | `univention-keycloak` implements an option to set client's authentication flow.
OK: Package built OK: Client specific authentication flow can be set OK: YAML Verified
<https://errata.software-univention.de/#/?erratum=5.0x758>