Camera RAW images plugin

Plugin to read RAW camera images based on LibRAW.

- Supersedes MR !86 
- Support to LibRaw 0.20 and 0.21-Beta
- Support to multi-shot images: use imageCount(), jumpToImage() to select the wanted shot
- By default generates 16-bits sRGB images using camera white balance and interpolation AHD
- Should fix CCBUG: 454208: on my Debian with KF5.96 and the pulgin installed, I see the preview of all my RAW files (ARW included) in Dolphin

News compared to V1 (MR !86)

- Fix possible stack overflow due to the huge size of LibRaw class
- Fix image allocation with Qt 6 (make use of QImageIOHandler::allocateImage()) 
- Support to XMP metapacket
- Support to quality option. For e.g. you can focus on quality (q = 10) or speed (q = 1)
- oss-fuzz available [here](https://github.com/mircomir/oss-fuzz/tree/raw_fuzz/projects/kimageformats)

autotests/CMakeLists.txt

@@ -139,6 +139,12 @@ if (OpenEXR_FOUND)
     # FIXME: OpenEXR tests
 endif()
 
+if (LibRaw_FOUND)
+    kimageformats_read_tests(
+        raw
+    )
+endif()
+
 find_package(Qt${QT_MAJOR_VERSION}Test ${REQUIRED_QT_VERSION} CONFIG QUIET)
 
 if(NOT TARGET Qt${QT_MAJOR_VERSION}::Test)