Always save TIFF with contiguous planar configuration

[radarhere]

Resolves #3622

If a TIFF image is opened with "separate" planar configuration, it is successfully read.

However, if that same image is saved, Pillow tries to keep the "separate" planar configuration from the input file, and the output image is broken.

This PR simply changes Pillow to always save "contiguous", and the output image is fixed.

[kmilos]

The forced libtiff writer cannot preserve it either?

[radarhere]

I don't know why the saved image is broken in main. However,

https://www.awaresystems.be/imaging/tiff/tifftags/planarconfiguration.html

The specification adds a warning that PlanarConfiguration=2 is not in widespread use and that Baseline TIFF readers are not required to support it.

So it seems like a good idea to avoid the "separate" setting for the sake of compatibility of our created images.

[kmilos]

Yeah, it's ok to play it safe for this case. I was just wondering if there was a remote chance of preserving the original image configuration, but unfortunately don't have the time to experiment right now...