Implement Observable POC #460

Job	Run time
ci (stable, stm32g431, log-itm)	46s
ci (stable, stm32g441, log-semihost)	1m 0s
ci (stable, stm32g431, log-rtt,defmt)	46s
ci (stable, stm32g441, cordic,log-rtt,defmt)	47s
ci (stable, stm32g471, log-itm)	47s
ci (stable, stm32g431, cordic,log-rtt,defmt)	48s
ci (stable, stm32g441, log-rtt,defmt)	47s
ci (stable, stm32g471, cordic,log-rtt,defmt)	52s
ci (stable, stm32g431, log-semihost)	44s
ci (stable, stm32g471, log-rtt,defmt)	46s
ci (stable, stm32g473, cordic,log-rtt,defmt)	55s
ci (stable, stm32g473, log-itm)	56s
ci (stable, stm32g471, log-semihost)	48s
ci (stable, stm32g473, log-rtt,defmt)	57s
ci (stable, stm32g473, log-semihost)	51s
ci (stable, stm32g474, cordic,log-rtt,defmt)	1m 9s
ci (stable, stm32g483, log-rtt,defmt)	55s
ci (stable, stm32g483, log-semihost)	47s
ci (stable, stm32g474, log-semihost)	49s
ci (stable, stm32g484, log-semihost)	53s
ci (stable, stm32g484, log-rtt,defmt)	52s
ci (stable, stm32g474, log-rtt,defmt)	1m 10s
ci (stable, stm32g483, cordic,log-rtt,defmt)	50s
ci (stable, stm32g491, log-itm)	49s
ci (stable, stm32g4a1, log-rtt,defmt)	1m 5s
ci (stable, stm32g484, cordic,log-rtt,defmt)	53s
ci (stable, stm32g483, log-itm)	46s
ci (stable, stm32g484, log-itm)	50s
ci (stable, stm32g4a1, log-semihost)	48s
ci (stable, stm32g491, log-rtt,defmt)	49s
ci (stable, stm32g4a1, log-itm)	51s
ci (stable, stm32g474, log-itm)	51s
ci (stable, stm32g491, cordic,log-rtt,defmt)	47s
ci (stable, stm32g4a1, cordic,log-rtt,defmt)	48s
ci (stable, stm32g491, log-semihost)	53s
ci (stable, stm32g441, log-itm)	45s
	30m 50s

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