Add littlefs file system and update Sys.IO.FileSystem and stream #148

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	1m 55s
build-target (SL_STK3701A, Debug, All)	9m 7s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	2m 53s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	7m 36s
build-target (M5Core2, Debug, ESP32)	3m 13s
build-target (M5Core2, Debug, All)	6m 18s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	2m 7s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	7m 23s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	3m 55s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	5m 22s
	49m 49s

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