Allow fingerprint login together with password login

## Problem

Currently if fingerprint login is enabled via installing the `fprintd` package and editing the `/etc/pam.d/lightdm` file to add `auth sufficient pam_fprintd.so` line then the greeter does not allow you to login by entering your password until the fingerprint module times out.

## Proposal

Allow users to login via fingerprint swipe or via entering their password whichever one is correctly attempted first.

## Prior Art

Stock ubuntu focal 20.04 gdm login screen lets you login using either fingerprint or entering password - one does not block the other.