MLX login needs to support AppID as an option.

**Is your feature request related to a problem? Please describe.**
MLX right now only can login using basic browser form. We need to add support for AppID login in the MLX login page.

The Kubeflow way of forcing login is based on domain path. However, MLX needs to force login based on user role, not the domain path. Thus, it needs to support the AppID login using the following documentations.
https://cloud.ibm.com/docs/appid?topic=appid-web-apps

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