The ExampleSpotlightLocator plug-in is a Viewer API-based plug-in that
implements a custom locator for drawing a geometry representation of
spotlights.
It is based on utility classes from the FnViewer/utils/FnBaseLocator.h header.

The FnBaseLocator code consists of a pre-configured ViewerDelegateComponent and
a ViewportLayer which track the scene graph for you, and which will draw
registered locators for any of their matching locations.
