Implement `send_break` support #1270

Job	Run time
Execute host-runable tests	2m 50s
Verifiy build on MSRV	5m 4s
Build rp2040-hal's examples	1m 17s
Build on-target-tests	51s
Build rp2040-hal's features	1m 26s
Check rp2040-hal for unused dependencies	2m 0s
	13m 28s

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