Blender Git Loki

Fix T84661: read jpg pixel density

For jpeg, an image.resolution was always based on the default 72dpi, now
read the pixel density from the jpeg_decompress_struct, convert
according to unit and store in IMBuf's ppm.

Not 100% sure of all implications tbh., files I have checked seem to work
as expected now in the context of the report.

Maniphest Tasks: T84661

Differential Revision: https://developer.blender.org/D10166