[TASK] code cleanup: restructure interfaces

- create a new folder ```lib/Phile/Gateway/``` and namespace ```Phile\Gateway\``` for all global interfaces
- create a new folder ```lib/Phile/ServiceLocator/``` and namespace ```Phile\ServiceLocator\```
- move all service locator interfaces to the new location, rename it, mark it as deprecated and create wrapper interfaces for the old interfaces which will be removed in v1.0.0
- move all other interfaces into the new location and namespace