Support more configuration on authentication providers

[edwardzjl]

Elyra now supports 5 authentication methods, no_authentication, kubernetes_service_account_token, dex_static_password, dex_ldap and dex_legacy.

Currently we are running kubeflow under protection of oidc-authservice which connects to our own idp, not dex.

Is it possible to provide a more flex configuration on authentication?

[ptitzler]

At first glance adding support would require implementation of a new authenticator class in https://github.com/elyra-ai/elyra/blob/main/elyra/pipeline/kfp/kfp_authentication.py. Contributions are welcome!