Support @koa/router

[feelform]

ref: https://github.com/elastic/require-in-the-middle/blob/master/README.md#api

## API

The require-in-the-middle module exposes a single function:

### `hook = Hook([modules][, options], onrequire)`

When called a `hook` object is returned.

Arguments:

- `modules` <string[]> An optional array of module names to limit which modules
  trigger a call of the `onrequire` callback. If specified, this must be the
  first argument. Both regular modules (e.g. `react-dom`) and
  sub-modules (e.g. `react-dom/server`) can be specified in the array.
- `options` <Object> An optional object containing fields that change when the
  `onrequire` callback is called. If specified, this must be the second
  argument.
  - `options.internals` <boolean> Specifies whether `onrequire` should be called
    when module-internal files are loaded; defaults to `false`.
- `onrequire` <Function> The function to call when a module is required.

The `onrequire` callback will be called the first time a module is
required. The function is called with three arguments:

- `exports` <Object> The value of the `module.exports` property that would
  normally be exposed by the required module.
- `name` <string> The name of the module being required. If `options.internals`
  was set to `true`, the path of module-internal files that are loaded
  (relative to `basedir`) will be appended to the module name, separated by
  `path.sep`.
- `basedir` <string> The directory where the module is located, or `undefined`
  for core modules.

Return the value you want the module to expose (normally the `exports`
argument).

We need to support koa-router and @koa/router.