We will reserve BOARD_FLASH_SIZE for the internal flash on stm32 flash processors, use HAL_PROGRAM_SIZE_LIMIT_KB in the general code base.
Notable change here is that boards with external flash will start to get features only available with more than 2MB of program storage
Adding of SRV_Channel_config allows defining the number of servo channels for inclusion in other libraries without pulling in all the other SRV_Channel logic.
Co-authored-by: Simon Maddison <81274690+Sypaq-MadMan@users.noreply.github.com>
