Add littlefs file system and update Sys.IO.FileSystem and stream #172

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	3m 54s
build-target (SL_STK3701A, Debug, All)	1m 11s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	2m 59s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	10m 6s
build-target (M5Core2, Debug, ESP32)	4m 36s
build-target (M5Core2, Debug, All)	1m 26s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	2m 27s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	1m 21s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	1m 37s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	6m 23s
	36m 0s

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