MAR-26: Implemented scaffolding for testing the ldap_server role:

- Fixed role documentation and example for the ldap_server ldap_entries
parameter.
- Fixed missing leading zero when setting mode for deployed files.
- Marked certain tasks for skipping Ansible linting on.
- Fixed invocation of local LDAP commands to use unix socket out of the
box (don't depend on LDAP client configuration).
- Default to state 'present' for ldap_entry (makes things a bit more
readable/clear).
- Added test data for backup and TLS.
- Added dummy default test file.