feat: support third party orm to interact with go-zero (#1286)

* fixes #987

* chore: fix test failure

* chore: add comments

* feat: support third party orm to interact with go-zero

* chore: refactor

zrpc/resolver/internal/etcdbuilder.go

@@ -0,0 +1,9 @@
+package internal
+
+type etcdBuilder struct {
+	discovBuilder
+}
+
+func (b *etcdBuilder) Scheme() string {
+	return EtcdScheme
+}