Draft: Resolve "implement docking/portable switch software"

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The software will start on boot and will

1. detect if current hardware can be docked/portable (gpi2, piboy or rg353x), if not just exit
2. detect current mode
3. if a switch has occurred (portable to docked or docked to portable), then do this:
   • change theme as requested (go2/next) if theme was not customized (see piboy docking software)
   • change audio sink output
   • force external or internal display off
   • disable internal joystick if docked (only for gpi2: echo "1-1.3:1.0" > /sys/bus/usb/drivers/xpad/unbind)
   • or lower priority for internal joystick (see piboy script)

For each hardware, some functions helper must exist:

• get current docking status (from gpio, kernel flag, drm)
• disable internal screen
• disable external video connector
• set internal audio speaker
• set external audio output

Tasks:

• write helper
• write service
• test on piboy
• test on gpi2
• test on rg353x
• allow 1080p for gpi2 (hdmi_group=1 and hdmi_mode=16 in recalbox-user-config.txt)

Related to #2358