Add `UnionToTuple` type

[Emiyaaaaa]

closed #819

I removed "unordered" from the name, I don't think unordered is necessary in the name, it can be specified in the docs, after all, no one would specifically need to generate an "unordered" array, it's just that the current limitation of ts leads to unordered arrays, so maybe later on it will be possible to optimise the result to be ordered.