[custom channels]: generate unique script keys for HTLCs #3478

Job	Run time
Format check	43s
cross compilation	4m 35s
Docker build check	3m 43s
Compilation check	50s
run itests	8m 54s
run itests postgres	17m 12s
Lint check	2m 42s
migration version check	11s
go mod check	37s
RPC check	1m 28s
run LiT tests	2m 23s
sample configuration check	47s
Sqlc check	43s
test vector check	54s
run unit tests (unit-race)	10m 50s
run unit tests (unit-cover)	2m 55s
run unit tests (unit dbbackend=postgres)	5m 22s
finish	4s
	1h 4m 53s

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