feat: support build tag to reduce binary size w/o k8s (#4323)

zrpc/resolver/internal/register_k8s.go

@@ -0,0 +1,13 @@
+//go:build !no_k8s
+
+package internal
+
+import "google.golang.org/grpc/resolver"
+
+var k8sResolverBuilder kubeBuilder
+
+// RegisterResolver registers the direct, etcd, discov and k8s schemes to the resolver.
+func RegisterResolver() {
+	register()
+	resolver.Register(&k8sResolverBuilder)
+}