Add the ability to move assets

Hi,

This is a follow up to Allow folders in /assets/ .

I can know lists assets in subfolders. The issue ie now I want to re-organize all my existing assets in subfolders, ie move them, rename them, etc. But I also don't want to break all the places where they are used. I can sort of do it one by one, by moving them, seeing where things break, going to update it, etc.

It would be nicer if there was a file manager of sorts that allowed me to move and rename assets, and that would automatically update all references to those assets. This would allow me to re-organize things without breaking any of the places where thosre assets are used.

Thanks for the consideration!