ui->waitingLabel is deleted and set to NULL when mode is PX4. Must
check for NULL before using it.

Instantiate a PX4 config view in PX4 mode from start, since boards with just the bootloader (or no working telemetry) cannot be flashed else.

Start move to single column layout for advanced parameters; Fix
crashing bug in PrimaryFlightDisplay when uas is removed and then
re-added; workaround compiler warning in GeneralBlockPanelKernel,