Send character over UART

This concerns the example in the folder AIdeck_examples/GAP8/test_functionalities/uart_send_char/. This was tested on GAP_SDK version 3.8.1.

The uart send character example sends a character over UART1, meant to be read out by the Crazyflie at the other end. Make sure that the AI-deck driver is force compiled in the crazyflie firmware as explained here.