Butcher command to work on selected region

### The Problem

When we use the //regen command on old bases on our server, the mobs are left untouched and have to be dealt with separately via the butcher command or builtin kill command. This is a particular problem with mine carts and armor stands.

### A Solution

An option to the butcher command to operate on the selected region as opposed to a radius.

### Alternatives

Continue to use the butcher or kill commands. This can get time consuming and some entities could still be left behind.

### Anything Else?

_No response_