Add a new portal error code for Auth::OIDC issues
Currently, when something goes wrong during an OIDC login flow, we display a generic "Error" message to the user.
SAML has specialized error messages (PE_SAML_ERROR, etc.)
We should at least let the user know that something went wrong with the OP, a default message could something like: "Error communicating with the OpenID Provider"
Added a new PE_OIDC_AUTH_ERROR returned by he Auth::OpenIDConnect module