Add littlefs file system and update Sys.IO.FileSystem and stream #108

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	2m 6s
build-target (SL_STK3701A, Debug, All)	1m 8s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	2m 16s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	6m 27s
build-target (M5Core2, Debug, ESP32)	4m 5s
build-target (M5Core2, Debug, All)	7m 2s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	2m 35s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	7m 29s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	2m 12s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	1m 7s
	36m 27s

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