EEVEE stores light probes using octahedral mapping. Compared to the previous
cubemap storage octahedral has less pixels. The 64x64 is becoming useless
and can be removed. This PR also enables generating light probe maps upto 4k.
Some issues were found: the offset of the sphere inside the atlas
was always set to mipmap level 0 offset. This was hidden because of the texture
wrapping. Also the offset was substracted from the local texture
coordinate when calculating the direction of the pixel. Might be that due
to the incorrect offset (mipmap level 0), the latter issue was never detected.
Pull Request: https://projects.blender.org/blender/blender/pulls/123074
55d75a1de3