Support mock with delay by configuration

[sorrycc]

Problem

Sometimes, we need to configure the delay of the mock globally.

Solution

新增 mock.delay 配置。

export default {
  mock: { delay: 1000 }
}

其他：delay 除了支持 number 之外，还支持字符串表示个范围，比如 delay: '500-1000'，就做 500ms 到 1000ms 的范围随机。（如果有更好的配置方式，请补充。）

Alternatives

No response

Importance

nice to have

Additional Information

No response