Multiple fixes around commitments and group keys #1647

Job	Run time
RPC check	1m 28s
Docker build check	4m 22s
cross compilation	13m 52s
Compilation check	55s
Lint check	3m 18s
go mod check	1m 10s
Sqlc check	33s
test vector check	1m 33s
Format check	31s
run itests	9m 37s
run itests postgres	14m 19s
run unit tests (unit-race)	8m 26s
run unit tests (unit-cover)	4m 21s
run unit tests (unit dbbackend=postgres)	6m 48s
	1h 11m 13s

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