Implements #108948 - support for custom point domain attributes for PLY
import and export. Notes:
- Custom attributes are always represented as scalar floats. PLY itself
has some data types that blender can't fully represent, e.g. double or
uint32, or some that fit into a float just fine but blender does not have
them as separate types (e.g. int16).
- When importing, any PLY vertex attribute that is not one of "standard"
names (position, normal, etc.) gets turned into a custom attribute.
- For exporting, more complex custom attributes (e.g. 2D/3D floats,
quaternions, colors) get turned into several PLY attributes, with "_x"
like suffix.
Custom attribute import/export is on by default in the UI.
Pull Request: https://projects.blender.org/blender/blender/pulls/114320
Reviewed By: Hans Goudey
0eb6aef3b0