Split config functionality into two classes

There is now Icinga\Application\Config as our ini configuration handler and
Icinga\Data\ConfigObject as our general configuration container.

refs #7147
Adjust usages of Icinga\Application\Config

refs #7147
Fix anonymous onSuccess callbacks
Do not redirect to the wizard in case of an empty config.ini
Re-add build/* to .gitignore
Merge branch 'master' into bugfix/drop-zend-config-7147

Conflicts:
	application/forms/LdapDiscoveryForm.php
Merge branch 'bugfix/drop-zend-config-7147'

fixes #7147