This makes the Blender binary 350 KB smaller. The largest change comes
from using `FunctionRef` instead of a template when gathering indices to
mix in the extrude node (which has no performance cost). The rest of the
change comes from consolidating uses of code generation for all
attribute types. This brings us a bit further in the direction of
unifying attribute propagation.
Pull Request: https://projects.blender.org/blender/blender/pulls/107823