Add the possibility of targetting only a certain angle

### The Problem

It takes a long time to properly texture a large mountain, even with the brush commands, especialy If I want to make only flat areas one block, and more steep spots a different block.

### A Solution

It would be cool if there was a mask setting or a //replace feature to select only certain angles of steepness, just like in FAWE

### Alternatives

_No response_

### Anything Else?

_No response_