Go to implementation should navigate to .js file instead of typescript type definitions

[Wenzil]

• VSCode Version: 1.12.1
• OS Version: OS X

Steps to Reproduce:

1. Open VS Code in a new workspace
2. npm init -y
3. npm install --save express
4. npm install --save-dev @types/express
5. In tsconfig.json:

{
    "compilerOptions": {
        "target": "es6",
        "module": "commonjs",
        "allowJs": true,
        "checkJs": true,
        "noEmit": true,
        "maxNodeModuleJsDepth": 1
    },
    "exclude": [
        "node_modules"
    ]
}

6. In index.js:

const express = require('express')

7. Right click on 'express', and choose Go to implementation

Expected behaviour:

The editor navigates to the .js file containing the module implementation (under node_modules/express)

Actual behaviour:

The editor navigates to the installed express type definitions

[Wenzil]

Somewhat related to #26329

[mjbvz]

Tracked upstream with microsoft/TypeScript#6209