[FEAT] A layer should create a context to share its layerview to its children.

[JonnyDawe]

At the moment getting access to a LayerView can be a bit fiddly, relying on asynchronous logic to wait for the mapview to load the layer or directly listening for the layerview-create event (which I only just discovered).

The current implementation of layer components only renders children to a layer when the layerview has been set. It would be great if it also provided the layerview via context to its children.