Components do not have to implement a base class anymore

In this PR I prepare the work to allow components to not implement the base class.

The main change is that Compose can no longer access component.id, component.context or component.inputs (because we have no guarantee these properties are exposed by component classes).

Instead of forcing components to expose these properties, it was fairly simple to refactor the code to get "id", "context" and "inputs" from other variables.