Increase default main task stack size to 16K

User's `init` function is called in main task.
After initialisation this task is destroyed and Sming continues to run
either in `tiT` task or `Sming` task, depending on whether networking
is enabled.

Sming/Arch/Esp32/Components/esp32/sdk/config/common

@@ -39,6 +39,7 @@ CONFIG_BT_NIMBLE_MESH=n
 CONFIG_ESP32_WIFI_SW_COEXIST_ENABLE=n
 
 # Mandatory Sming framework changes
+CONFIG_ESP_MAIN_TASK_STACK_SIZE=16384
 CONFIG_ESP_TASK_WDT_TIMEOUT_S=8
 
 # Required by HardwareSPI library