GH-2268 update the deb package to not depend on latest jre

* `openjdk-8-jre` is now recommended
* the package now depends on `desktop-file-utils`
* the desktop icon has been updated to the current one

application/package/ubuntu/multimc/usr/share/applications/multimc.desktop

@@ -0,0 +1,16 @@
+[Desktop Entry]
+Categories=Game;
+Exec=/opt/multimc/run.sh
+Icon=/opt/multimc/icon.svg
+Keywords=game;
+MimeType=
+Name=MultiMC 5
+Path=
+StartupNotify=true
+Terminal=false
+TerminalOptions=
+Type=Application
+X-DBUS-ServiceName=
+X-DBUS-StartupType=
+X-KDE-SubstituteUID=false
+X-KDE-Username=