Add a script to package kiwix-desktop in a AppImage.

AppImage is a tools to create application running in all linux.
See https://appimage.org/

scripts/create_kiwix-desktop_appImage.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+
+set -e
+
+INSTALLDIR=${1:-$PWD/BUILD_native_dyn/INSTALL}
+APPDIR=${2:-$PWD/AppDir}
+
+#TODO We should have our icon
+ICONFILE=/usr/share/icons/hicolor/48x48/apps/gvim.png
+
+# Create structure
+mkdir -p $APPDIR/usr/{bin,lib,share} $APPDIR/usr/share/applications $APPDIR/usr/share/icons/hicolor/48x48/apps
+# Copy our files
+cp $INSTALLDIR/bin/kiwix-desktop $APPDIR/usr/bin/
+cp $INSTALLDIR/lib/x86_64-linux-gnu/*.so* $APPDIR/usr/lib
+# Remove it as it break with linuxdeployqt (should we compile without it) ?
+rm $APPDIR/usr/lib/libmagic.so*
+# Copy nss lib (to not conflict with host's ones)
+cp -a /usr/lib/x86_64-linux-gnu/nss $APPDIR/usr/lib
+cp $ICONFILE $APPDIR/usr/share/icons/hicolor/48x48/apps/kiwix-desktop.png
+# TODO we should have our .desktop
+tee $APPDIR/usr/share/applications/kiwix-desktop.desktop <<EOF > /dev/null
+[Desktop Entry]
+Name=Kiwix
+Exec=kiwix-desktop %F
+Icon=kiwix-desktop
+Type=Application
+Terminal=false
+StartupNotify=true
+NoDisplay=false
+EOF
+
+# Get linuxdeployqt
+wget https://github.com/probonopd/linuxdeployqt/releases/download/continuous/linuxdeployqt-continuous-x86_64.AppImage
+chmod a+x linuxdeployqt-continuous-x86_64.AppImage
+
+# Fill with all deps libs and so
+./linuxdeployqt-continuous-x86_64.AppImage $APPDIR/usr/bin/kiwix-desktop -verbose=3 -bundle-non-qt-libs
+# Fix the RPATH of QtWebEngineProcess [TODO] Fill a issue ?
+patchelf --set-rpath '$ORIGIN/../lib' $APPDIR/usr/libexec/QtWebEngineProcess
+# Build the image.
+./linuxdeployqt-continuous-x86_64.AppImage $APPDIR/usr/share/applications/kiwix-desktop.desktop -verbose=3 -bundle-non-qt-libs -appimage   #