feat: response filter

[patrickmao1]

Added a feature that enables user to pass in a user defined responseFilter function in request init option.

This function allows user to:

1. post-process response data so they won't need to deal with it after each call of request.
2. not struggle with writing another wrapper around the request instance & lose request's syntactic sugar (i.e. .get .post ...)

[yesmeck]

Why not use response interceptor?

[patrickmao1]

How do you use response interceptor to achieve this? _parseRequest method in wrapped-fetch is called after the user defined response interceptor calls and is excepting raw response. I can't return anything but the original response type in the interceptor

[clock157]

you can do it like this:

/**
 * 对将结果的状态层剥掉
 */
request.use(async(ctx, next) => {
  await next();
  if(ctx.res && ctx.res.code === 200) {
    ctx.res = ctx.res.data;
  }
});