kvdb: make lnd/kvdb a submodule

kvdb/go.mod

@@ -0,0 +1,28 @@
+module github.com/lightningnetwork/lnd/kvdb
+
+require (
+	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f
+	github.com/btcsuite/btcwallet/walletdb v1.3.4
+	github.com/coreos/go-semver v0.3.0 // indirect
+	github.com/coreos/go-systemd v0.0.0-20191104093116-d3cd4ed1dbcf // indirect
+	github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f // indirect
+	github.com/dustin/go-humanize v1.0.0 // indirect
+	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e // indirect
+	github.com/google/uuid v1.1.1 // indirect
+	github.com/gorilla/websocket v1.4.2 // indirect
+	github.com/grpc-ecosystem/grpc-gateway v1.14.3 // indirect
+	github.com/json-iterator/go v1.1.9 // indirect
+	github.com/lightningnetwork/lnd/healthcheck v1.0.0
+	github.com/stretchr/testify v1.7.0
+	github.com/tmc/grpc-websocket-proxy v0.0.0-20190109142713-0ad062ec5ee5 // indirect
+	go.etcd.io/bbolt v1.3.5-0.20200615073812-232d8fc87f50
+	go.etcd.io/etcd v3.4.14+incompatible
+	go.uber.org/zap v1.14.1 // indirect
+	golang.org/x/crypto v0.0.0-20200709230013-948cd5f35899 // indirect
+)
+
+// Fix incompatibility of etcd go.mod package.
+// See https://github.com/etcd-io/etcd/issues/11154
+replace go.etcd.io/etcd => go.etcd.io/etcd v0.5.0-alpha.5.0.20201125193152-8a03d2e9614b
+
+go 1.15