Add littlefs file system and update Sys.IO.FileSystem and stream #183

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	2m 38s
build-target (SL_STK3701A, Debug, All)	12m 10s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	2m 33s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	6m 10s
build-target (M5Core2, Debug, ESP32)	5m 43s
build-target (M5Core2, Debug, All)	6m 47s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	2m 18s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	7m 48s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	5m 18s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	8m 11s
	59m 36s

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