feat: support tls for etcd client (#1390)

* feat: support tls for etcd client

* chore: fix typo

* refactor: rename TrustedCAFile to CACertFile

* docs: add comments

* fix: missing tls registration

* feat: add InsecureSkipVerify config for testing

core/discov/internal/registry.go

@@ -337,6 +337,9 @@ func DialClient(endpoints []string) (EtcdClient, error) {
 		cfg.Username = account.User
 		cfg.Password = account.Pass
 	}
+	if tlsCfg, ok := GetTLS(endpoints); ok {
+		cfg.TLS = tlsCfg
+	}
 
 	return clientv3.New(cfg)
 }