Allow single block to be replaced with the clipboard

### The Problem

I would like to scatter multi-block structures, such as custom trees, around my world, by marking the locations of the structure with one block, and then replacing said block with the structure. Currently, I can use //replace to replace a region with a structure of the same size. However, as far as I can tell, there is no option to replace a single block with a larger structure.

### A Solution

I imagine placing structures by placing a single block where I would like the base of the structure to be. Then, a command would let me replace each block with an entire structure. It would be especially interesting if I could pull from a list of structures (saved as schematics), and/or randomly rotate the structures.

### Alternatives

I can manually copy/paste structures to the desired location, but this is somewhat time consuming. It also does not allow for easy randomization of the structures.

### Anything Else?

_No response_