Instances on Elements should align to edge direction

Instances on Elements is great; however, when used on edges, it aligns to the mesh face rather than the edge direction. Some cases, especially using mesh edges to instance objects when full orientation control is not needed, want to align to the mesh direction instead.

Implementation-wise, this is simple. The current implementation uses the "edge normal" (which doesn't necessarily exist) to align the rotation to the incoming Z, then uses the direction to align to the incoming X. The desired implementation is to use the direction to align to incoming Z (the second alignment is not needed).

More generally, it might be helpful to have more knobs for adjusting how the rotation alignment happens, but implementing this might be impractical.