While adding tests for subd import I discovered that our vertex crease
data was imported incorrectly.
This PR adds tests and fixes:
- We tried to read crease sharpness data as ints instead of floats. This
caused the import process to early-return, meaning we never load any
data at all
- Empty USD data would still cause us to create the `crease_vert`
attribute unnecessarily
- Sharpness data needs clamped to 0-1 to handle USD's SHARPNESS_INFINITE
value of 10.0
- We need to fill the `crease_vert` span with 0's since incoming USD
data may not have values set for all the verts
Pull Request: https://projects.blender.org/blender/blender/pulls/131516
76c699ada5