Integration with custom react renderers

Hey, thanks for the nice tool.

I am the maintainer of https://github.com/konvajs/react-konva, it is a custom react renderer that draw into canvas instead of DOM.

I am curious if it may be possible to make `react-scan` work with custom fibers as well. So renders such as `react-konva` or `@react-three/fiber` can be scanned too.

In `react-konva` we can provide a function similar to `element.getBoundingClientRect()` to provide position of an element.