StandbyRTCBKPSRAMMode_Measure() function

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