Configure_ADC() function

In case re-use of this function outside of this example: This function includes checks of ADC hardware constraints before executing some configuration functions. - In this example, all these checks are not necessary but are implemented anyway to show the best practice usages corresponding to reference manual procedure. (On some STM32 series, setting of ADC features are not conditioned to ADC state. However, in order to be compliant with other STM32 series and to show the best practice usages, ADC state is checked anyway with same constraints). Software can be optimized by removing some of these checks, if they are not relevant considering previous settings and actions in user application. - If ADC is not in the appropriate state to modify some parameters, the setting of these parameters is bypassed without error reporting: it can be the expected behavior in case of recall of this function to update only a few parameters (which update fulfills the ADC state). Otherwise, it is up to the user to set the appropriate error reporting in user application. Peripheral configuration is minimal configuration from reset values. Thus, some useless LL unitary functions calls below are provided as commented examples - setting is default configuration from reset.