Make use of our sparse value writer in more places. Namely, when using
animated Camera or Light properties, this will prevent a needless stream
of unchanging values being written into the USD file [1]. Skeletons and
armatures benefit too but less so as typically the primary benefit only
applies to the comparatively small `scale` transform attribute, which
typically remains unchanged from frame to frame.
The newly added `set_attribute` common code can, and eventually will, be
used to reduce boilerplate elsewhere where we do the same sparse writing
dance.
Ref #130759
Pull Request: https://projects.blender.org/blender/blender/pulls/131333
Jesse Yurkovich
f92bfe0f0b