Add support for policy files

[hwo-wd]

New parameters for the installation of policy files:

Variable	Description	Default
keycloak_quarkus_policies	List of policy definitions; see below	[]

Policy definition:

keycloak_quarkus_policies:
  - name: xato-net-10-million-passwords.txt    # required, resulting file name
    url: https://github.com/path/to/policy.txt # required, url for download
    type: password-blacklists                  # optional, defaults to `password-blacklists`;
                                               # supported values: [`password-blacklists`]

Fix #224