Group key witness support #1448

Job	Run time
cross compilation	13m 8s
Docker build check	4m 27s
Format check	33s
Compilation check	47s
run itests	8m 31s
run itests postgres	10m 22s
Lint check	2m 55s
go mod check	40s
RPC check	1m 48s
Sqlc check	25s
test vector check	1m 16s
run unit tests (unit-race)	6m 5s
run unit tests (unit-cover)	4m 10s
run unit tests (unit dbbackend=postgres)	4m 34s
	59m 41s

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