Add DWA compression level option

[TodicaIonut]

DWA compression level option:

DWA compression level 0 - 1000 Range

[kmilos]

If this ends up being added (overkill for dt IMHO, anything wrong w/ OpenEXR defaults?), then it makes sense to expose control for zip level as well for ZIPS/ZIP at the same time (also seems to be useful for DAWAA/B)...

[github-actions]

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[robeastham]

Good idea @TodicaIonut. I agree @kmilos exposing zip compression level too makes sense.

I actually think this would be an excellent option to have and not overkill in some scenarios. I'm seeing better results with jpeg at 99 quality with only 8bits per channel, vs DWAA & DWAB 16bit & 32bit for my application. Not what I would expect, but explained by the fact that I think the default compression on DWAA and DWAB is set quite high for Darktable.

In the meantime, while no GUI for this exisits, does anyone know what the current defaults for DWAA and DWAB is/are and how one might change them?

I've had a little dig around in the source, if I wanted to build from source and set this value for myself for DWAA or DWAB is this the place to start looking:

https://github.com/AcademySoftwareFoundation/openexr/blob/main/src/lib/OpenEXR/ImfCompressor.cpp

I'm quite new to Darktable and so I'm not sure if the line here:

exr_set_dwa_compression_level (_ctxt, 0, hdr.dwaCompressionLevel ());

..is something that can be set as a darktablerc value or when using darktable-cli. If so then I guess I might not need to go to the trouble of trying to build from source.

Any pointers anyone can provide for how to set this compression value in the short term would be most welcome.