arduino-1.8.13-linuxarm Install fails with No such file or directory and cannot create /root/.config/mimeapps.list.new

```
pi@raspberrypi:~/Downloads $ tar -x -f arduino-1.8.13-linuxarm.tar.xz
pi@raspberrypi:~/Downloads $ sudo mv arduino-1.8.13 /opt
pi@raspberrypi:~/Downloads $ sudo /opt/arduino-1.8.13/install.sh
Adding desktop shortcut, menu item and file associations for Arduino IDE...

touch: cannot touch '/root/.config/mimeapps.list': No such file or directory
/usr/bin/xdg-mime: 848: /usr/bin/xdg-mime: cannot create /root/.config/mimeapps.list.new: Directory nonexistent

done!
```

Despite the above errors, I am able to run arduino from /opt/arduino-1.8.13.

```
pi@raspberrypi:~/Downloads $ uname -a
Linux raspberrypi 5.10.17-v7l+ #1414 SMP Fri Apr 30 13:20:47 BST 2021 armv7l GNU/Linux

pi@raspberrypi:~/Downloads $ /opt/arduino-1.8.13/java/bin/java -version
java version "1.8.0_191"
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) Server VM (build 25.191-b12, mixed mode)
```

Start with /opt/arduino-1.8.13/install.sh and reproduce the install command on the reported Raspberry Pi environment. Check how the script invokes desktop integration and handles /root/.config; the work is done when installation completes without the missing-directory errors and the shortcut, menu item, and file associations are created.

Written by the indexing model from the issue text.