Fix Dialog/DialogOutlet/Transition behavior

[DavidVollmers]

• Rename IgnisOutletComponentBase to IgnisContentProviderComponentBase and rework its behavior
• Rename OutletBase to ContentHostBase and rework its behavior
• Remove IOutlet, IOutletComponent, IOutletRegistry and IOutletRegistrySubscriber interfaces
• Introduce IContentHost, IContentProvider, IContentRegistry and IContentRegistrySubscriber interfaces
• Update Dialog component to work with the new classes and interfaces
• Update Transition to work with the new classes and interfaces if the transition contains a Dialog child component