Support UNC paths on Windows

[lukts30]

Reading from UNC seems to be working. But writing does not.

Expected behavior: commands should be equivalent.

PS C:\> CompressonatorCLI "\\?\C:\Users\lukas\Documents\rdm4\rdm4lib\rdm\excavator_tycoons_diff_0.dds" "C:\Users\lukas\Documents\rdm4\rdm4lib\gltf_out1\excavator_tycoons_diff_0.png"
Processing progress = 75   MipLevel  7 FaceOrSlice  0
Done Processing

PS C:\> CompressonatorCLI "\\?\C:\Users\lukas\Documents\rdm4\rdm4lib\rdm\excavator_tycoons_diff_0.dds" "\\?\C:\Users\lukas\Documents\rdm4\rdm4lib\gltf_out1\excavator_tycoons_diff_0.png"
Processing progress = 75   MipLevel  7 FaceOrSlice  0
Error: saving image failed, write permission denied or format is unsupported for the file extension.

Actual behavior: using an UNC path as destination fails.

[NPCompress]

@lukts30 This needs to be investigated further for UNC IO support. Its good that read works with CMP DDS lib API, for saving to png files we use Qt lib's qimage->save(). Will have to investigate if UNC is supported by that API.

[Dimoks]

On Ubuntu (WSL 2):

Path to compressonatorcli-bin in $PATH

compressonatorcli-bin "/mnt/d/images/dds/voice_icon.dds" "/mnt/d/images/png/voice_icon.png"

Processing source : /mnt/d/images/dds/voice_icon.dds Processing destination: /mnt/d/images/png/voice_icon.png Processing progress = 95MipLevel 1 FaceOrSlice 1 Error: saving image failed, write permission denied or format is unsupported for the file extension.

compressonatorcli-bin -ff DDS -fx PNG "/mnt/d/images/dds/DIALOG/" "/mnt/d/images/png/DIALOG"

Processing source : /mnt/d/images/dds/DIALOG/dialog_BG.dds Processing destination: /mnt/d/images/png/DIALOG/dialog_BG.png Processing progress = 100MipLevel 1 FaceOrSlice 1 Error: saving image failed, write permission denied or format is unsupported for the file extension.