build(projects): 依赖升级，规范目录

src/enum/common.ts

@@ -0,0 +1,6 @@
+/** 请求头的content-type类型 */
+export enum ContentType {
+  json = 'application/json',
+  formUrlencoded = 'application/x-www-form-urlencoded',
+  formData = 'multipart/form-data'
+}

src/enum/index.ts

@@ -0,0 +1 @@
+export { ContentType } from './common';