Handle wildcard imports: import * as something from '@ember/something'

https://github.com/babel/ember-cli-babel/issues/170#issue-246272427

> The [`import` statement](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import) supports importing all named exports into an object.
>
>For example, instead of this
>
>```js
>import {
> alias as computedAlias,
> and as computedAnd,
> // ...
>} from '@ember/object/computed';
>import { decoratedPropertyWithRequiredParams } from '../utils/decorator-macros';
>
>export const alias = decoratedPropertyWithRequiredParams(computedAlias);
>```
>
> you could just do this
>
> ```js
> import * as computed from '@ember/object/computed';
> import { decoratedPropertyWithRequiredParams } from '../utils/decorator-macros';
>
> export const alias = decoratedPropertyWithRequiredParams(computed.alias);
> ```
>
> But apparently, the latter does not work. :slightly_frowning_face:
>
> ```
> Could not find module `@ember/object/computed` imported from `ember-decorators/object/computed`
> ```

https://github.com/babel/ember-cli-babel/issues/170#issuecomment-318635180
> We would need to handle wildcard import in babel-plugin-ember-modules-API-polyfill. This seems reasonable to me though. We would need to check if the specified module contains only exports from a single namespace or multiple. If multiple namespaces we would have to build up the intermediate POJO that would be used.

Start by tracing how the Babel plugin handles Ember module imports, then read the linked ember-cli-babel issue and comment. The work should make `import * as something from '@ember/something'` resolve correctly, including modules with one or multiple export namespaces; done means the documented wildcard example no longer reports the module-not-found error.

Written by the indexing model from the issue text.