This reduces the number of file writes we do for config.php and therefor
hopefully helps lowering the chances for empty config.php files

* files_encryption
* files_versions
* files_trashbin
* tests
* status.php
* core
* server container

* this needs to be properly fixed by a proper organisation of the base.php
* introduced fixDIInit() in AllConfig that moves the injection
  of DatabaseConnection to a later point in time
* problems mostly because of the autoconfig setup

* keep old static methods - mapped to new ones and deprecated
* removed deleteApp, getUsers, getApps because they are unused
* make AllConfig unit tests more robust against not cleaned up environments

* introduce SystemConfig to avoid DI circle (used by database connection which is itself needed by AllConfig that itself contains the methods to access the config.php which then would need the database connection - did you get it? ;))
* use DI container and use that method in legacy code paths (for easier refactoring later)
* create and use getSystemConfig instead of query() in DI container

Fixes https://github.com/owncloud/core/issues/10624

Fix copy paste fail

Add unittest for comma separated headers

Revert 3rdparty

Conflicts:
	lib/private/vcategories.php