Support for DNG from DJI Mini 5 Pro

[jchnkl]

The DNG files from the DJI Mini 5 Pro seem not to be supported, at least darktable 5.2.1 throws an error:

     8,1252 [rawspeed] (2025-09-28T18-50-53+0200_20250928185053_0003_D.dng) void rawspeed::AbstractDngDecompressor::decompress() const, line 250: Too many errors encountered. Giving up. First Error:
virtual rawspeed::Buffer::size_type rawspeed::LJpegDecoder::decodeScan(), line 108: Unsupported predictor mode: 6

I've uploaded samples to raw.pixls.us but they don't show up in the repository (at least I can't find them there). I can provide the samples here or by other means if necessary.

Thank you very much!

[kmilos]

x-ref #189