Allow new 1.5.2 tunnels to have height and width but unspecified depth

## Describe your suggestion
right now depth is a required argument for custom tunnels, thats dumb

## Settings
allow #tunnel to take 0 arguments (infinite 1x2), 2 arguments (heightXwidth infinite) or 3 arguments (heightxwidth and depth)

## Context
the custom tunnels will likely be used to mine incredibly long nether highways on anarchy servers and putting in too big of a number for depth causes an error

## 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.