[V3 Todo] New default "auto" relative layout engine (with auto popup/tooltip alignment)#4

The decision between `fit-parent` and `fit-content` is irritating and unclear. If the user wants to tweak the icon position sufficiently, and/or have tooltip/popups as well, you can't easily get it right with certain anchoring without falling back to `fit-parent`. `fit-parent` is not ideal because it means you must define the icon size. We would rather defer that to the component itself. A new `auto` layout engine is to be added as a clear default that covers all of these use cases. It should: * Always defer size of the icon to the component itself (like `fit-content`). No expensive recalcs if the size changes. Just works dynamically. * The user should be able to define common icon anchor positions like `top`, `bottom-right` etc etc, as well as provide a custom value as a `%` value relative to the icons own size. * The user should be able to use tooltips/popups and they just work with positioning similar to the default but automatically scaling to the size of the icon. * All positions to support tweaking by pixel values relative to the anchor point.