Add debos recipe for raspberrypi ARM64-based boards

This adds a debos recipe for building a desktop image for a ARM64-based
RaspberryPi. It include a lightweight desktop, that is LXDE, create a
default user "pi" that has sudo access rights. As on Raspbian, the "pi"
user is automatically logged in via lightdm. The buster debian splash is
also automatically enabled

debos/overlays/lxde-pi/home/pi/.config/lxpanel/LXDE/config

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+[Command]
+Logout=lxde-logout

debos/overlays/lxde-pi/home/pi/.config/lxpanel/LXDE/panels/panel

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+# lxpanel <profile> config file. Manually editing is not recommended.
+# Use preference dialog in lxpanel to adjust config when you can.
+
+Global {
+  edge=top
+  align=left
+  margin=0
+  widthtype=percent
+  width=100
+  height=26
+  transparent=1
+  tintcolor=#000000
+  alpha=101
+  setdocktype=1
+  setpartialstrut=1
+  autohide=0
+  heightwhenhidden=0
+  usefontcolor=1
+  fontcolor=#ffffff
+  background=0
+  backgroundfile=/usr/share/lxpanel/images/background.png
+}
+Plugin {
+  type=space
+  Config {
+    Size=2
+  }
+}
+Plugin {
+  type=menu
+  Config {
+    image=/usr/share/lxde/images/lxde-icon.png
+    system {
+    }
+    separator {
+    }
+    item {
+      command=run
+    }
+    separator {
+    }
+    item {
+      image=gnome-logout
+      command=logout
+    }
+  }
+}
+Plugin {
+  type=launchbar
+  Config {
+    Button {
+      id=pcmanfm.desktop
+    }
+    Button {
+      id=lxde-x-www-browser.desktop
+    }
+  }
+}
+Plugin {
+  type=space
+  Config {
+    Size=4
+  }
+}
+Plugin {
+  type=wincmd
+  Config {
+    Button1=iconify
+    Button2=shade
+  }
+}
+Plugin {
+  type=space
+  Config {
+    Size=4
+  }
+}
+Plugin {
+  type=pager
+  Config {
+  }
+}
+Plugin {
+  type=space
+  Config {
+    Size=4
+  }
+}
+Plugin {
+  type=taskbar
+  expand=1
+  Config {
+    tooltips=1
+    IconsOnly=0
+    AcceptSkipPager=1
+    ShowIconified=1
+    ShowMapped=1
+    ShowAllDesks=0
+    UseMouseWheel=1
+    UseUrgencyHint=1
+    FlatButton=0
+    MaxTaskWidth=150
+    spacing=1
+  }
+}
+Plugin {
+  type=volume
+  Config {
+    VolumeMuteKey=XF86AudioMute
+    VolumeDownKey=XF86AudioLowerVolume
+    VolumeUpKey=XF86AudioRaiseVolume
+  }
+}
+Plugin {
+  type=tray
+  Config {
+  }
+}
+Plugin {
+  type=dclock
+  Config {
+    ClockFmt=%R
+    TooltipFmt=%A %x
+    BoldFont=0
+    IconOnly=0
+    CenterText=0
+  }
+}
+Plugin {
+  type=launchbar
+  Config {
+    Button {
+      id=lxde-screenlock.desktop
+    }
+    Button {
+      id=lxde-logout.desktop
+    }
+  }
+}

debos/overlays/lxde-pi/home/pi/.config/lxpanel/launchtaskbar.cfg

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+[special_cases]
+synaptic=synaptic-pkexec
+soffice.bin=libreoffice
+x-terminal-emulator=lxterminal

debos/overlays/lxde-pi/home/pi/.config/pcmanfm/LXDE/desktop-items-0.conf

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+[*]
+wallpaper_mode=crop
+wallpaper_common=1
+wallpaper=/home/pi/.config/pcmanfm/LXDE/pi_white.jpg
+desktop_bg=#000000
+desktop_fg=#ffffff
+desktop_shadow=#000000
+desktop_font=Sans 12
+show_wm_menu=0
+sort=mtime;ascending;
+show_documents=0
+show_trash=0
+show_mounts=0
+