Update package dependencies in AppImageBuilder

The changes include adding several packages to the list of dependencies for the AppImage-builder, such as libgtk,
librsvg2, imagemagick and icon themes. Furthermore, adjustments were made to the runtime environment variables
(GDK_PIXBUF_MODULEDIR and GDK_PIXBUF_MODULE_FILE). Excluded file paths were also updated to exclude unnecessary
documentation files.

Contributes to CURA-11132

packaging/AppImage-builder/AppImageBuilder.yml.jinja

@@ -47,17 +47,26 @@ AppDir:
     - sourceline: deb https://packagecloud.io/slacktechnologies/slack/debian/ jessie
         main
     include:
-      - xdg-desktop-portal-kde:amd64
+      - xdg-desktop-portal-kde
+      - libgtk-3-0
+      - librsvg2-2
+      - librsvg2-common
+      - libgdk-pixbuf2.0-0
+      - libgdk-pixbuf2.0-bin
+      - libgdk-pixbuf2.0-common
+      - imagemagick
+      - shared-mime-info
+      - gnome-icon-theme-symbolic
+      - hicolor-icon-theme
     exclude: []
   files:
-    include:
-      - usr/share/icons/hicolor/*
+    include: []
     exclude:
-    - usr/share/man
-    - usr/share/doc/*/README.*
-    - usr/share/doc/*/changelog.*
-    - usr/share/doc/*/NEWS.*
-    - usr/share/doc/*/TODO.*
+      - usr/share/man
+      - usr/share/doc/*/README.*
+      - usr/share/doc/*/changelog.*
+      - usr/share/doc/*/NEWS.*
+      - usr/share/doc/*/TODO.*
   runtime:
     env:
       APPDIR_LIBRARY_PATH: "$APPDIR/usr/lib/x86_64-linux-gnu:$APPDIR/lib/x86_64-linux-gnu:$APPDIR/usr/lib:$APPDIR/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders"
@@ -65,7 +74,8 @@ AppDir:
       QT_PLUGIN_PATH: "$APPDIR/qt/plugins"
       QML2_IMPORT_PATH: "$APPDIR/qt/qml"
       QT_QPA_PLATFORMTHEME: xdgdesktopportal
-      XDG_DATA_HOME: "$APPDIR/usr/share"
+      GDK_PIXBUF_MODULEDIR: $APPDIR/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders
+      GDK_PIXBUF_MODULE_FILE: $APPDIR/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache
     path_mappings:
       - /usr/share:$APPDIR/usr/share
   test: