Add role prefix to role specifig variable to avoid conflicts when
using multiples role on the same machine on the same play.

(IcingaWeb2) LDAP:

- procedure to automatically issue service credetinals to authenticate
  with the ldap server.

- starttls secured ldap connection with service account.

- use of the variable `base_dn` instead of hard-coded values in config
  files.

(IcingaWeb2) CONFIGURATION:

- fixed rsync parameters.

- resource renaming.

- User last official deb package from matrix.org

- Revised LDAP integration:
  * ldap_server, ldap_domain [ ldap_basedn ] config vraiables.
  * Bind a protected service account with a service password and
    start-tls

- Hardcoded matrix.lilik.it --> {{ ansible_hostname }}.{{ domain }}

- Sqlite -> Postgres

New variables:

- matrix_domain | default($domain)

Role to configure nextcloud with LDAP User backend.

First test passed.

New modules:

- occ:
  set coniguration values using `php occ` nextcloud command-line tool.