Support specifying OIDC query parameters via the config

[thaddeuskkr]

Description

I'd like to see support for changing the URL parameters of authentication requests to OIDC providers. For example, I'd like to be able to customize the prompt parameter, so that it can be set to select_account or consent. This is especially useful for Google OIDC, as it defaults to not having the account selector at all.

[tale]

Aiming to support this in 0.6.1, sorry for the late response. It should be fairly trivial.