feat: add target property to proxy option paths

Author: bjohansebas

test/server/proxy-option.test.js

@@ -24,6 +24,7 @@ const proxyOptionPathsAsProperties = [
   },
   {
     context: "/foo",
+    target: `http://localhost:${port1}`,
     pathRewrite: (_path, req) => {
       if (/\.html$/.test(req.path || req.url)) {
         return "/index.html";
@@ -34,6 +35,7 @@ const proxyOptionPathsAsProperties = [
   },
   {
     context: "/proxy/async",
+    target: `http://localhost:${port1}`,
     router: async (req, res) => {
       if (/\/proxy\/async$/.test(req.path || req.url)) {
         return new Promise((resolve) => {