StandbyRTCBKPSRAMMode_Measure() function

This function configures the system to enter Standby mode with RTC clocked by or LSI and with Backup SRAM ON for current consumption measurement purpose. STANDBY Mode with RTC clocked by LSI and BKPSRAM ==================================================== - RTC Clocked by LSI - Backup SRAM ON - IWDG OFF - Automatic Wakeup using RTC clocked by LSI (after ~20s)