Add littlefs file system and update Sys.IO.FileSystem and stream #138

Job	Run time
build-target (SL_STK3701A, Debug, AzureRTOS)	1m 57s
build-target (SL_STK3701A, Debug, All)	9m 30s
build-target (ST_STM32F769I_DISCOVERY, Debug, ChibiOS)	2m 12s
build-target (ST_STM32F769I_DISCOVERY, Debug, All)	9m 12s
build-target (M5Core2, Debug, ESP32)	3m 29s
build-target (M5Core2, Debug, All)	5m 53s
build-target (NXP_MIMXRT1060_EVK, Debug, FreeRTOS-NXP)	5m 9s
build-target (NXP_MIMXRT1060_EVK, Debug, All)	5m 40s
build-target (TI_CC1352R1_LAUNCHXL, Debug, TI, 915)	2m 44s
build-target (TI_CC1352R1_LAUNCHXL, Debug, All, 915)	7m 13s
	52m 59s

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