Don't break snow layers when building

## Describe your suggestion
The vanilla game allows you to replace snow layers with blocks without first breaking the snow layer. When Baritone is placing blocks, it will first break the snow layer, and then place the block. This is far less efficient for building then just placing directly.

## Settings
If buildIgnoreExisting is enabled, or snow_layer is in buildIgnoreBlocks, snow layers would not be replaced.

## Context
When building in a snowy biome, it is irritating when Baritone destroys the snow layer unnecessarily. It would be much more efficient if it just replaced the block.

## Final checklist
- [x] I know how to properly use check boxes
- [x] I have not used any OwO's or UwU's in this issue.