[3/3]: Implement `Consumer` on `chainWatcher` and resolvers #449

Job	Run time
lint code	3m 54s
check commits	34m 11s
cross compilation	32m 5s
RPC and mobile compilation check	2m 1s
check pinned dependencies (google.golang.org/grpc v1.59.0)	3s
sample configuration check	49s
check pinned dependencies (github.com/golang/protobuf v1.5.3)	6s
Sqlc check	27s
run unit tests (btcd unit-cover)	16m 18s
run macOS itest	35m 0s
run unit tests (unit tags="kvdb_etcd")	19m 1s
check release notes updated	3s
run unit tests (unit tags="kvdb_postgres")	17m 32s
run unit tests (unit tags="kvdb_sqlite")	15m 55s
run ubuntu itests (btcd, backend=btcd cover=1)	22m 9s
run unit tests (btcd unit-race)	35m 30s
run windows itest	6m 22s
run ubuntu itests (bitcoind, backend=bitcoind cover=1)	30m 6s
run unit tests (unit-module)	1m 1s
run ubuntu itests (bitcoind-notxindex, backend="bitcoind notxindex")	30m 7s
run ubuntu itests (bitcoind-rpcpolling, backend="bitcoind rpcpolling" cover=1)	29m 37s
run ubuntu itests (bitcoind-etcd, backend=bitcoind dbbackend=etcd)	41m 28s
run ubuntu itests (bitcoind-postgres, backend=bitcoind dbbackend=postgres)	51m 46s
run ubuntu itests (bitcoind-sqlite, backend=bitcoind dbbackend=sqlite)	30m 31s
run ubuntu itests (bitcoind-postgres-nativesql, backend=bitcoind dbbackend=postgres nativesql=true)	52m 29s
run ubuntu itests (bitcoind-sqlite-nativesql, backend=bitcoind dbbackend=sqlite nativesql=true)	31m 28s
run ubuntu itests (neutrino, backend=neutrino cover=1)	26m 27s
finish	8s
	9h 26m 34s

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