Add littlefs file system and update Sys.IO.FileSystem and stream #112

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	4m 9s
build-target (SL_STK3701A, Debug, All)	6m 15s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	2m 17s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	6m 2s
build-target (M5Core2, Debug, ESP32)	3m 0s
build-target (M5Core2, Debug, All)	5m 5s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	1m 54s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	5m 41s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	1m 36s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	6m 43s
	42m 42s

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