Add littlefs file system and update Sys.IO.FileSystem and stream #123

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	9m 46s
build-target (SL_STK3701A, Debug, All)	6m 18s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	16m 19s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	5m 45s
build-target (M5Core2, Debug, ESP32)	3m 29s
build-target (M5Core2, Debug, All)	4m 52s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	1m 36s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	5m 7s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	15m 1s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	5m 3s
	1h 13m 16s

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