Provide implementations of `ToTensor` for common data types

[benbaarber]

Right now, implementing ToTensor looks a bit hairy. Down the road, I will want to make this simpler, but a good intermediate step is to provide implementations for a couple common state/action data types.

[benbaarber]

Added blanket implementations for T where T: Into<Data>, as well as Vec<E> and Vec<[E; A]>