Add littlefs file system and update Sys.IO.FileSystem and stream #142

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	3m 59s
build-target (SL_STK3701A, Debug, All)	6m 56s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	2m 15s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	7m 18s
build-target (M5Core2, Debug, ESP32)	4m 28s
build-target (M5Core2, Debug, All)	4m 59s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	3m 34s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	1m 13s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	2m 32s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	1m 15s
	38m 29s

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