Initiating Login from a Third Party

[spalte]

Implement OIDC Initiating Login from a Third Party (https://openid.net/specs/openid-connect-core-1_0.html#ThirdPartyInitiatedLogin)

Concretely this means implementing a /login route in KHEOPS UI that takes three query parameters, iss, login_hint, and target_link_uri. When the route is called first make sure that iss matches KHEOPS_OIDC_PROVIDER. If it does, trigger authenticateOidc with:

const payload = {
    redirectPath: $target_link_uri,
    login_hint: $login_hint
};