Add baby_fto.

[lgarron]

I'm currently using the name baby_fto in Twizzle / scramble.cubing.net / timer.cubing.net, because:

• I don't think the historical name (Skewb Diamond) is particularly intuitive if you're not a puzzle builder, and having the full prefix "Skewb" might cause UX/coding issues.
• "2×2 FTO" isn't quite fully established, and it's unclear if this will match generalizations for other puzzles in the future.

But we may want to figure out a scheme for the latter, e.g. 2x2_fto or fto_2_layer

[jfly]

I don't have any useful feedback on the slug, sorry. I don't feel bad about having to change this in the future.

[lgarron]

I don't have any useful feedback on the slug, sorry. I don't feel bad about having to change this in the future.

Alright, I'm okay with that as well, thanks!

Aliases are easy to implement, and I think we can figure out braking name change releases in the future if needed.