feat: Add Hook named export (#88)

`import-in-the-middle` has some ESM interop issues.

From
[here](open-telemetry/opentelemetry-js#4546 (comment)):

> Specifically, namespace imports are required by the ESM spec to be
objects. IITM's top-level export is not an object, but a callable
function

This causes
[issues](open-telemetry/opentelemetry-js#4717)
with some bundlers. Obviously bundled imports will not go through
`import-in-the-middle` but using it should not inhibit bundlers as iitm
can still hook build-in modules.

This adds a `Hook` named export and changes one cjs and esm test to
use that new export.

README.md

@@ -18,7 +18,7 @@ imported in ESM files, regardless of whether they're imported statically or
 dynamically.
 
 ```js
-import Hook from 'import-in-the-middle'
+import { Hook } from 'import-in-the-middle'
 import { foo } from 'package-i-want-to-modify'
 
 console.log(foo) // whatever that module exported

index.js

@@ -89,5 +89,6 @@ Hook.prototype.unhook = function () {
 }
 
 module.exports = Hook
+module.exports.Hook = Hook
 module.exports.addHook = addHook
 module.exports.removeHook = removeHook

test/hook/dynamic-import.js

@@ -2,7 +2,7 @@
 //
 // This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2021 Datadog, Inc.
 
-const Hook = require('../../index.js')
+const { Hook } = require('../../index.js')
 const { strictEqual } = require('assert')
 
 Hook((exports, name) => {

test/hook/static-import-default.mjs

@@ -2,7 +2,7 @@
 //
 // This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2021 Datadog, Inc.
 
-import Hook from '../../index.js'
+import { Hook } from '../../index.js'
 import barMjs from '../fixtures/something.mjs'
 import barJs from '../fixtures/something.js'
 import { strictEqual } from 'assert'