Use `is_manifold_like`

CombinatorialSpaces.jl offers the [`is_manifold_like`](https://algebraicjulia.github.io/CombinatorialSpaces.jl/dev/simplicial_sets/#CombinatorialSpaces.SimplicialSets.is_manifold_like-Tuple{AbstractDeltaSet1D}) function which tests certain combinatorial-properties of a manifold-like simplicial set. (Note that some not-tested-for-properties, such as whether a manifold is a single connected component, do not obstruct us simulating physics on them.)

We should call `is_manifold_like` as part of our `gensim` pipeline. This will catch bugs early and provide helpful error messages.

Note that `is_manifold_like` uses the older `d` reference implementation, and so using `dec_differential` there should be upstreamed.