Implement Observable POC #358

Job	Run time
ci (stable, stm32g431, log-rtt,defmt)	35s
ci (stable, stm32g431, log-itm)	33s
ci (stable, stm32g431, log-semihost)	32s
ci (stable, stm32g431, cordic,log-rtt,defmt)	32s
ci (stable, stm32g441, log-rtt,defmt)	31s
ci (stable, stm32g441, log-itm)	34s
ci (stable, stm32g441, log-semihost)	35s
ci (stable, stm32g441, cordic,log-rtt,defmt)	37s
ci (stable, stm32g471, log-rtt,defmt)	31s
ci (stable, stm32g471, log-itm)	33s
ci (stable, stm32g471, log-semihost)	33s
ci (stable, stm32g471, cordic,log-rtt,defmt)	33s
ci (stable, stm32g473, log-rtt,defmt)	32s
ci (stable, stm32g473, log-itm)	35s
ci (stable, stm32g473, log-semihost)	33s
ci (stable, stm32g473, cordic,log-rtt,defmt)	35s
ci (stable, stm32g474, log-rtt,defmt)	1s
ci (stable, stm32g474, log-itm)	35s
ci (stable, stm32g474, log-semihost)	36s
ci (stable, stm32g474, cordic,log-rtt,defmt)	36s
ci (stable, stm32g483, log-rtt,defmt)	1s
ci (stable, stm32g483, log-itm)	1s
ci (stable, stm32g483, log-semihost)	1s
ci (stable, stm32g483, cordic,log-rtt,defmt)	1s
ci (stable, stm32g484, log-rtt,defmt)	1s
ci (stable, stm32g484, log-itm)	1s
ci (stable, stm32g484, log-semihost)	1s
ci (stable, stm32g484, cordic,log-rtt,defmt)	1s
ci (stable, stm32g491, log-rtt,defmt)	1s
ci (stable, stm32g491, log-itm)	1s
ci (stable, stm32g491, log-semihost)	1s
ci (stable, stm32g491, cordic,log-rtt,defmt)	1s
ci (stable, stm32g4a1, log-rtt,defmt)	1s
ci (stable, stm32g4a1, log-itm)	1s
ci (stable, stm32g4a1, log-semihost)	1s
ci (stable, stm32g4a1, cordic,log-rtt,defmt)	1s
	10m 58s

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