Add option to disable on-board LED

[goldenegg]

Is your feature request related to a problem? Please describe. Provide an option to turn off the LED on the RPi.

Describe the solution you'd like An option can be added in the settings, allowing the user to disable the on-board LED. This option exists in RoPiee.

Describe alternatives you've considered Taping over the LED is the only other real option, but not preferred.

Additional context Nothing more to add.