[keycloak-user] SAML IDP seamless SSO

[Devlin, Martin]

Hi,

I am setting up a SAML IDP. The user will already exist in Keycloak, I want
that user linked to the IDP.

What I want is for the user to be linked invisibly, without having to do
anything.

I have disabled the following in the First Broker Login flow:

```
first broker login/idp-review-profile set to DISABLED
first broker login/idp-confirm-link set to DISABLED
first broker login/idp-email-verification set to DISABLED
```

This gets rid of the dialogs to confirm profile and email verification.

But there's another setting that I can't disable: "
Username Password Form For Identity Provider Reauthentication"

So as it is the user has to authenticate against the IDP (which is what I
want) but then also against Keycloak (which I don;t want).

Thanks,

Martin