Espressif ESP32 boards

Samples that demonstrate the use of Espressif ESP32 boards in Zephyr.

• Deep SleepUse deep sleep with wake on timer, GPIO, and EXT1 sources on ESP32.
• Flash EncryptionEncrypt/decrypt data stored in flash memory using ESP32 flash encryption feature.
• Light SleepUse light sleep mode on ESP32 to save power while preserving the state of the memory, CPU, and peripherals.
• Memory-Mapped FlashWrite data into scratch area and read it using flash API and memory-mapped pointer.
• SPIRAMAllocate memory from SPIRAM.
• XTAL32K Watchdog Timer (WDT)Trigger watchdog interrupt on external 32K crystal failure.