Blender 3.5 moved UV layers to a generic attribute also accessible from
the new `uv` property of the UV layer. The old API still works for now,
but is slower and may be removed in 4.0, so this patch updates FBX IO to
use the new `uv` property.
There is no performance difference between accessing the UVs through the
foreach_get/set functions of the attribute and the `uv` property.