chanbackup, server, rpcserver: put close unsigned tx, remote signature and commit height to SCB #15825

Job	Run time
check commits	10m 34s
cross compilation	12m 1s
check pinned dependencies (google.golang.org/grpc v1.59.0)	3s
lint code	3m 40s
check pinned dependencies (github.com/golang/protobuf v1.5.3)	4s
check release notes updated	4s
run macOS itest	53m 54s
RPC and mobile compilation check	2m 16s
sample configuration check	50s
Sqlc check	2m 49s
run ubuntu itests (btcd, backend=btcd cover=1)	36m 5s
run unit tests (btcd unit-cover)	17m 17s
run ubuntu itests (bitcoind, backend=bitcoind cover=1)	41m 39s
run unit tests (unit tags="kvdb_etcd")	19m 40s
run windows itest	45m 1s
run ubuntu itests (bitcoind-notxindex, backend="bitcoind notxindex")	42m 31s
run unit tests (unit tags="kvdb_postgres")	18m 15s
run ubuntu itests (bitcoind-rpcpolling, backend="bitcoind rpcpolling" cover=1)	43m 35s
run unit tests (unit tags="kvdb_sqlite")	17m 4s
run ubuntu itests (bitcoind-etcd, backend=bitcoind dbbackend=etcd)	59m 44s
run unit tests (btcd unit-race)	37m 40s
run ubuntu itests (bitcoind-postgres, backend=bitcoind dbbackend=postgres)	1h 20m 50s
run unit tests (unit-module)	1m 2s
run ubuntu itests (bitcoind-sqlite, backend=bitcoind dbbackend=sqlite)	44m 53s
run ubuntu itests (bitcoind-postgres-nativesql, backend=bitcoind dbbackend=postgres nativesql=true)	1h 22m 5s
run ubuntu itests (bitcoind-sqlite-nativesql, backend=bitcoind dbbackend=sqlite nativesql=true)	45m 47s
run ubuntu itests (neutrino, backend=neutrino cover=1)	38m 50s
finish	5s
	12h 38m 18s

Provide feedback