esp32/boards: Add Silicognition wESP32 board configuration.

For rev 7+ boards with 16MB of flash.  Partition table allocates 2.4 MiB
for MicroPython, 11 MiB for the filesystem.

ports/esp32/boards/SIL_WESP32/mpconfigboard.cmake

+set(SDKCONFIG_DEFAULTS
+    boards/sdkconfig.base
+    boards/sdkconfig.ble
+    boards/sdkconfig.240mhz
+    boards/SIL_WESP32/sdkconfig.board
+)
+
+if(NOT MICROPY_FROZEN_MANIFEST)
+    set(MICROPY_FROZEN_MANIFEST ${MICROPY_PORT_DIR}/boards/manifest.py)
+endif()

ports/esp32/boards/SIL_WESP32/mpconfigboard.h

+#define MICROPY_HW_BOARD_NAME "Silicognition wESP32"
+#define MICROPY_HW_MCU_NAME "ESP32"

ports/esp32/boards/SIL_WESP32/sdkconfig.board

+# 16 MB flash
+
+CONFIG_ESPTOOLPY_FLASHSIZE_4MB=
+CONFIG_ESPTOOLPY_FLASHSIZE_8MB=
+CONFIG_ESPTOOLPY_FLASHSIZE_16MB=y
+CONFIG_ESPTOOLPY_FLASHSIZE="16MB"
+
+# Fast flash
+
+CONFIG_FLASHMODE_QIO=y
+CONFIG_ESPTOOLPY_FLASHFREQ_80M=y
+CONFIG_ESP32_REV_MIN_1=y
+
+# OTA
+
+CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y
+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions-16MiB-ota.csv"
+
+# Network name
+
+CONFIG_LWIP_LOCAL_HOSTNAME="wESP32"

ports/esp32/partitions-16MiB-ota.csv

+# Partition table for MicroPython with OTA support using 16MB flash
+# Notes: the offset of the partition table itself is set in
+# $IDF_PATH/components/partition_table/Kconfig.projbuild.
+# Name,   Type, SubType, Offset,   Size,     Flags
+nvs,      data, nvs,     0x9000,   0x4000,
+otadata,  data, ota,     0xd000,   0x2000,
+phy_init, data, phy,     0xf000,   0x1000,
+ota_0,    app,  ota_0,   0x10000,  0x270000,
+ota_1,    app,  ota_1,   0x280000, 0x270000,
+vfs,      data, fat,     0x4f0000, 0xb10000,