Add ESP8266_RTOS_SDK bulid configuration

[QB4-dev]

Hello.
This is default configuration for https://github.com/espressif/ESP8266_RTOS_SDK
I am using this config to craete spiffs images for ESP8266

[TranPhucVinh]

Thanks @QB4-dev, that works perfectly. I'm now able to flash the binary file built from mkspiffs ESP8266 RTOS SDK to ESP8266 board. Here are my steps:

With partitions.csv:

# Name,   Type, SubType, Offset,  Size, Flags
# Note: if you change the phy_init or app partition offset, make sure to change the offset in Kconfig.projbuild
nvs,      data, nvs,     0x9000,  0x6000,
phy_init, data, phy,     0xf000,  0x1000,
factory,  app,  factory, 0x10000, 0xF0000,
storage,  data, spiffs,  0x210000, 1M,

Run this command to generate bin file data_output from all files inside folder data:

./mkspiffs -c data/ -b 4096 -p 256 -s 0x100000 data_output

Then flash

esptool.py -p /dev/ttyUSB0 write_flash 0x210000 data_output

All file inside folder data now can be read and written with ESP8266 RTOS SDK.