Ansible need clue to allow idempotency.

These scripts are read-only, and hence idempotent by nature:

• export-zip-for-user.php
• export-opml-for-user.php
• list-users.php
• user-info.php

These scripts are not safe as there modify FresRSS's internal data:

• do-install.php should be launched only if data/do-install.txt exists (otherwise, installation has already been launched)

• create-user.php should be launched only if the user does not exist (see list-users.php for that)

• delete-user.php should be launched only if the user does exist (see list-users.php for that)

• import-for-user.php should be launched only if the user has no feed (there is no way to check that)

• actualize-user.php returns 0 if there is new articles, 1 if there is no new articles

• reconfigure.php is a mystery (as it is not documented on cli/README.md)