cdc: add uart status notification support. #521

Job	Run time
set-matrix	4s
build (arm-gcc) / family (-b feather_nrf52840_express)	42s
build (arm-gcc) / family (-b max32666fthr)	1m 13s
build (esp-idf) / family (-b espressif_p4_function_ev)	8m 43s
build (arm-gcc) / family (-b metro_m4_express)	55s
build (esp-idf) / family (-b espressif_p4_function_ev -f1 CFG_TUD_DWC2_DMA_ENABLE -f1 CFG_TUH_DWC2_DMA_ENABLE)	8m 25s
build (arm-gcc) / family (-b lpcxpresso11u37)	33s
build (esp-idf) / family (-b espressif_s3_devkitm)	8m 13s
build (arm-gcc) / family (-b ra4m1_ek)	40s
build (esp-idf) / family (-b espressif_s3_devkitm -f1 CFG_TUD_DWC2_DMA_ENABLE)	7m 58s
build (arm-gcc) / family (-b raspberry_pi_pico)	2m 2s
build (arm-gcc) / family (-b raspberry_pi_pico2)	2m 10s
build (arm-gcc) / family (-b stm32f072disco)	44s
build (arm-gcc) / family (-b stm32f723disco)	50s
build (arm-gcc) / family (-b stm32f723disco -f1 CFG_TUH_DWC2_DMA_ENABLE)	1m 0s
build (arm-gcc) / family (-b stm32h743nucleo)	57s
build (arm-gcc) / family (-b stm32h743nucleo -f1 CFG_TUD_DWC2_DMA_ENABLE)	50s
build (arm-gcc) / family (-b stm32g0b1nucleo)	46s
hil-tinyusb	2m 12s
	48m 57s

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