Mine gravel from the top

## Describe your suggestion
Mining gravel/sand from the top is faster because when mining from the bottom it has to fall before you can mine any more.

## Settings
- Mine gravity-affected blocks from the top, true/false?

## Context
Baritone currently mines gravel based on what's closest, which is usually the bottom if you're clearing out an area. Which means it'll go on to the next block until it finishes falling, then stop, then mine that gravel, and it'll repeat for the entire stack of gravel, which is kinda slow. If you mine from the top, Baritone won't have any issue with gravel seemingly disappearing and re-appearing, since it won't be turning into falling_block entities.

## Final checklist
- [x] I have not used any OwO's or UwU's in this issue.