Ask the user to use the name plugin if a yaml file is used to unregister

Hello

fusiondirectory-plugins-manager code must test if the user pass a yaml file or not.

If it is a yaml file then we display the message that he must use the name plugin.

It will avoid the next error.

root@defd9c121ed2:/# fusiondirectory-plugins-manager  --unregister-plugin /etc/fusiondirectory/yaml/systems/description.yaml 
Error while deleting branch : /etc/fusiondirectory/yaml/systems/description.yaml !
PHP Fatal error:  Uncaught FusionDirectory\Ldap\Exception: No such object (32)(matched dn: ou=pluginManager,dc=nodomain) in /usr/share/php/FusionDirectory/FusionDirectory/Ldap/Result.php:117
Stack trace:
#0 /usr/share/php/FusionDirectory/FusionDirectory/Tools/PluginsManager.php(261): FusionDirectory\Ldap\Result->assert()
#1 [internal function]: FusionDirectory\Tools\PluginsManager->deletePluginRecord('/etc/fusiondire...')
#2 /usr/share/php/FusionDirectory/FusionDirectory/Cli/Application.php(198): call_user_func(Array, Array)
#3 /usr/share/php/FusionDirectory/FusionDirectory/Tools/PluginsManager.php(118): FusionDirectory\Cli\Application->runCommands()
#4 /usr/sbin/fusiondirectory-plugins-manager(29): FusionDirectory\Tools\PluginsManager->run(Array)
#5 {main}
  thrown in /usr/share/php/FusionDirectory/FusionDirectory/Ldap/Result.php on line 117
root@defd9c121ed2:/# fusiondirectory-plugins-manager  --unregister-plugin systems                                            
Deleted systems from LDAP successfully.

Cheers