sdkconfig: use sdkconfig.defaults

Use sdkconfig.defaults instead of maintaining a full sdkconfig in git.
The sdkconfig resulting from running `./utils.sh install` with this
commit should be the same as before this commit.

We can re-evaluate some of these values at a later stage, but we should
first start with identical sdkconfig. This will make bisecting easier.
If we were to change sdkconfig values in this commit, reverting the
commit would completely revert the use of sdkconfig.defaults.

Fixes: #21

sdkconfig.defaults

@@ -0,0 +1,77 @@
+# Reasons for choosing some of these values can be found in the git history:
+# git log -- sdkconfig.willow
+
+# CONFIG_BOOTLOADER_APP_ANTI_ROLLBACK is not set
+CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y
+CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_PERF=y
+CONFIG_COMPILER_OPTIMIZATION_PERF=y
+# CONFIG_ETH_USE_SPI_ETHERNET is not set
+CONFIG_ESP32S3_DATA_CACHE_64KB=y
+CONFIG_ESP32S3_DATA_CACHE_LINE_64B=y
+CONFIG_ESP32S3_DEFAULT_CPU_FREQ_240=y
+CONFIG_ESP32S3_INSTRUCTION_CACHE_32KB=y
+CONFIG_ESP32S3_SPIRAM_SUPPORT=y
+CONFIG_ESP32_S3_BOX_BOARD=y
+# CONFIG_ESP32_WIFI_NVS_ENABLED is not set
+CONFIG_ESP32_WIFI_STATIC_RX_BUFFER_NUM=10
+CONFIG_ESP32_WIFI_AMSDU_TX_ENABLED=y
+CONFIG_ESP32_WIFI_RX_BA_WIN=6
+CONFIG_ESPTOOLPY_FLASHSIZE_16MB=y
+CONFIG_ESPTOOLPY_MONITOR_BAUD_2MB=y
+CONFIG_ESP_HTTP_CLIENT_ENABLE_BASIC_AUTH=y
+CONFIG_ESP_MAIN_TASK_STACK_SIZE=16384
+# CONFIG_ESP_PHY_CALIBRATION_AND_DATA_STORAGE is not set
+CONFIG_ESP_PHY_RF_CAL_FULL=y
+CONFIG_ESP_TASK_WDT_PANIC=y
+CONFIG_ESP_TASK_WDT_TIMEOUT_S=10
+CONFIG_ESP_TLS_CLIENT_SESSION_TICKETS=y
+CONFIG_ESP_TLS_INSECURE=y
+CONFIG_ESP_TLS_SKIP_SERVER_CERT_VERIFY=y
+CONFIG_FREERTOS_HZ=1000
+CONFIG_GDMA_CTRL_FUNC_IN_IRAM=y
+CONFIG_LCD_RGB_ISR_IRAM_SAFE=y
+CONFIG_LOG_TIMESTAMP_SOURCE_SYSTEM=y
+# CONFIG_LV_BUILD_EXAMPLES is not set
+CONFIG_LV_COLOR_16_SWAP=y
+CONFIG_LV_DISP_DEF_REFR_PERIOD=10
+CONFIG_LV_FS_POSIX_LETTER=65
+CONFIG_LV_FS_POSIX_PATH=""
+CONFIG_LV_FS_POSIX_CACHE_SIZE=0
+CONFIG_LV_FONT_DEFAULT_MONTSERRAT_24=y
+# CONFIG_LV_FONT_MONTSERRAT_14 is not set
+CONFIG_LV_MEMCPY_MEMSET_STD=y
+CONFIG_LV_MEM_CUSTOM=y
+CONFIG_LV_MEM_CUSTOM_INCLUDE="stdlib.h"
+CONFIG_LV_USE_FS_POSIX=y
+CONFIG_LV_USE_FONT_SUBPX=y
+CONFIG_LWIP_DHCP_GET_NTP_SRV=y
+CONFIG_LWIP_DHCP_MAX_NTP_SERVERS=1
+CONFIG_LWIP_LOCAL_HOSTNAME="willow"
+CONFIG_LWIP_TCPIP_TASK_AFFINITY_CPU0=y
+CONFIG_MBEDTLS_CERTIFICATE_BUNDLE_MAX_CERTS=1000
+CONFIG_MBEDTLS_EXTERNAL_MEM_ALLOC=y
+# CONFIG_MBEDTLS_HARDWARE_AES is not set
+# CONFIG_MBEDTLS_HARDWARE_SHA is not set
+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions_willow.csv"
+CONFIG_PARTITION_TABLE_FILENAME="partitions_willow.csv"
+CONFIG_PTHREAD_DEFAULT_CORE_0=y
+CONFIG_SPIFFS_MAX_PARTITIONS=6
+CONFIG_SPIRAM_ALLOW_STACK_EXTERNAL_MEMORY=y
+CONFIG_SPIRAM_FETCH_INSTRUCTIONS=y
+CONFIG_SPIRAM_IGNORE_NOTFOUND=y
+CONFIG_SPIRAM_MALLOC_ALWAYSINTERNAL=0
+CONFIG_SPIRAM_MALLOC_RESERVE_INTERNAL=16384
+CONFIG_SPIRAM_MODE_OCT=y
+CONFIG_SPIRAM_RODATA=y
+CONFIG_SPIRAM_SPEED_80M=y
+CONFIG_SPIRAM_TRY_ALLOCATE_WIFI_LWIP=y
+CONFIG_SPI_MASTER_IN_IRAM=y
+CONFIG_SPI_SLAVE_IN_IRAM=y
+CONFIG_SR_MN_CN_NONE=y
+CONFIG_SR_MN_EN_MULTINET6_QUANT=y
+# CONFIG_SR_MN_EN_NONE is not set
+CONFIG_SR_WN_LOAD_MULIT_WORD=y
+CONFIG_SR_WN_WN9_ALEXA_MULTI=y
+CONFIG_SR_WN_WN9_HIESP_MULTI=y
+CONFIG_SR_WN_WN9_HILEXIN_MULTI=y