[3d] add an image input as reference images dynamically

(From community feedback):
do you think it’d be possible to add an image input to the load3D node? That way, we could drop in bg reference images dynamically.
I’m working with a few friends in archviz, and this small tweak could really smooth out some workflows

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-4093-3d-add-an-image-input-as-reference-images-dynamically-20b6d73d365081918c29dd8075931eea) by [Unito](https://www.unito.io)