ipa-replica-install --setup-adtrust: check for package ipa-server-trust-ad
    
    When adding the option --setup-adtrust to ipa-replica-install,
    we need to check that the package freeipa-server-trust-ad is
    installed.
    To avoid relying on OS-specific commands like yum, the check is instead
    ensuring that the file /usr/share/ipa/smb.conf.empty is present
    (this file is delivered by the package).
    When the check is unsuccessful, ipa-replica-install exits with an error
    message.
    
    Fixes: https://pagure.io/freeipa/issue/7602
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>