[Feature]: Additional triangular blocks

[ashe-attacc]

Describe the feature

Hi! I had the idea for new triangle type blocks to be added, as I noticed they were missing and it's made building specific structures a bit difficult.

Something like this. Similar to the prism but it fills out a whole block. (using Little Tiles to illustrate my idea) (And apologies if these are already planned or were already suggested before.)

[XFactHD]

These sound like a sensible addition to me. I've got plans to extend on the set of prism blocks anyway, so this fits in quite well. I'll add it to the ever growing list