The idea is simple: do not provide full topology to OpenSubdiv, leave
edges creation to OpenSubdiv itself. This solves issues with non-manifold
meshes which were known to fail, including the ones from T52059.
On a positive side we can simplify our side of converter, keeping code
shorter.
it is still possible that we'll need to ensure all loops has same
winding, but that is less things to worry about.
