Feature Proposal: Viewer - Point Annotation - Custom Point Component

[joseph-bayer]

I think it would be really cool to support custom svgs for annotation points. A good real-world example of how this would be useful is map pins.

This would be different from annotations with non-rectangular polygons outlined in a manifest, since the each point's size could stay consistent despite zoom level (as proposed here), and since this is more of a stylistic choice that should be made by the frontend as opposed to being made in a manifest.

I propose that we update the config to have an "annotations" object for various annoation-related options and add a prop to that object to support this.

If this sounds like a good idea to you, just let me know! I'd be totally up to implement this.