In very old OpenEXR version there was a limit on the channel names, which meant
the pass names needed to be short like "DiffDir". Change them to be longer like
"Diffuse Direct".
* This breaks forward compatibility. Old Blender version will lose links when
reading compositing node setups with such passes, but #146571 will fix it
for 4.5 LTS.
* Add-ons, scripts and compositing setups in other applications that rely on these
names will also break.
* The find_by_type function for render passes has also been removed, as this was
already deprecated and replaced by find_by_name.
* We assume spaces in the name are ok, since we have passes with them already
and have not seen reports about compatibility issues.
Pull Request: https://projects.blender.org/blender/blender/pulls/142731
78ae7ec392