Refactor all ConfigSources to support lists

[timo0]

With #17088 we introduced lists.

Before this was not supported by the ConfigSource still it was possible by convention to get comma separated values as lists.

Now we have some "hack" in the ConfigurationImpl.java to support both methods:

        if (!propertiesService.isListProperty(propertyName)) {
            final String value = getValue(propertyName);
            values = ConfigListUtils.createList(value);
        } else {
            values = getValues(propertyName);
        }

This should be refactored and in the same way the AbstractConfigSource can be refactored to support list properties in a generic way