This reverts commit ddae0483, reversing
changes made to e55b563d.

Issue #15685

**Bug**

Create an empty project with a `launch.json` like this:

```
{
    "version": "0.2.0",
    "configurations": [
    ]
}
```

Try to start debugging.

See an exception message

**Fix**
Instead of returning undefined for the promise result, return a promise of null like we do in other cases.

closes #15685

Fixes #15650

fixes #15643

- Create a model for default settings and key bindings
- Move default settings actions as editor contributions

Fixes #13064

Fixes #15571

This reverts commit 463438e7.

This extracts the JS content from the webview html into its own file which is loaded using preload instead.

- Create a model for default settings and key bindings
- Move default settings actions as editor contributions