This is the first step for refactoring the lightcache system.
Each probe instance (as in `Object`) will now store its own baked data.
The data is currently stored in uncompressed readable format.
This introduces two new operators for baking to avoid confusion with
the previous light baking pipeline. These do nothing other than
creating empty caches that will be populated by EEVEE later on.
The DNA storage is made to be able to include multiple caches
in case of baked simulation over time but it isn't yet supported.
I prefer to keep the implementation simple for now as the long term
goals for this feature are uncertain.
There is still a type flag (`LightProbeObjectCache.cache_type`) that
will be used for versioning.
The naming convention of structs is a bit weird but that's all I
found in order to avoid interfering with the old scene light cache
that is still used by (old) EEVEE.
Related task #106449.
Pull Request: https://projects.blender.org/blender/blender/pulls/106808
a8feb20e1c