Fix XCF parasites metadata in QImage and support to ICC profile
- Fix parasite "gimp-comment" not set due to null QImage
- Support to parasite "icc-profile" using Qt 5.14+ API
- Added parasite "gimp-image-metadata" as QImage metadata "XML:org.gimp.xml"
- Added a XCF with XML metadata and icc prifile embedded in autotest folder (generated by GIMP 2.10.30)
- Tested with Qt 5.15.2 and Qt 6.2.3 under Windows and Qt 6.2.3 under macOS