This PR fixes the service subscriber interface on the container utils. The Problem is the namespace change of the interface between symfony 3 and 5. This PR add an abstract class the implement the correct interface based on the existing class. This is only needed until contao 4.4 support is dropped.
[x] Create AbstractServiceSubscriber
[x] Make Container Util extend from AbstractServiceSubscriber
[x] Refactor Utils-Class to extend from AbstractServiceSubscriber
This PR fixes the service subscriber interface on the container utils. The Problem is the namespace change of the interface between symfony 3 and 5. This PR add an abstract class the implement the correct interface based on the existing class. This is only needed until contao 4.4 support is dropped.