Groom assets can no longer be created without curves data

It used to be possible to create an empty Groom assets without an Alembic file. However, this is no longer possible because curve data is required

This workflow is useful to create grooms that only contain mesh cards (no strands) versus having to generate unused strands in a separate DCC tool, import that Alembic file, delete the strands and adjust the LODs and then have groom bounds calculated from the strands that were deleted instead of the mesh cards.

Ideally, the groom bounds would be based on the static mesh provided for cards.

1. Attempt to create an empty groom and assign a material

Expected

An empty groom can be created

Actual

An empty groom cannot be created and curve data is required.