Print transform-level stats on task completion.

[donmccurdy]

Currently each transform in the @gltf-transform/functions package includes a manual cmd: Complete print statement at its end. It's easy to forget those when adding new functions and they're not particularly useful. It might be better if the document.transform(...) runner just printed those statements automatically, perhaps including time.

[cmd]: Completed in XXms

Note that one transform may invoke another, often before/after it executes, so any timing may need to be contextualized.