调整 api 目录，代码优化

src/api/system/menu.js

@@ -0,0 +1,40 @@
+import request from '@/utils/request'
+
+export function getMenusTree() {
+  return request({
+    url: 'api/menus/tree',
+    method: 'get'
+  })
+}
+
+export function buildMenus() {
+  return request({
+    url: 'api/menus/build',
+    method: 'get'
+  })
+}
+
+export function add(data) {
+  return request({
+    url: 'api/menus',
+    method: 'post',
+    data
+  })
+}
+
+export function del(id) {
+  return request({
+    url: 'api/menus/' + id,
+    method: 'delete'
+  })
+}
+
+export function edit(data) {
+  return request({
+    url: 'api/menus',
+    method: 'put',
+    data
+  })
+}
+
+export default { add, edit, del, getMenusTree }