Fix bug when loading models on child entities of controllers

[mrxz]

Description:
The various controls components handle the model-loaded event to configure the controller models. However, they don't check where the model-loaded event originates from. In case a child entity loads a model, the controls components would incorrectly assume it's the controller model that just loaded in.

This actually causes issues in A-Painter where the model-loaded event of the brush-tip would trigger the onModelLoaded for the oculus-touch-controls (and others).

Changes proposed:

• Include a guard in onModelLoaded checking that the event didn't originate from any child element

[dmarcos]

Thanks!