feat: identifiers

[AndersDJohnson]

Supports dependents/node-dependency-tree#147.

Support passing an option identifiers: true to return imported identifiers in addition to paths.

For named imports or re-exports like this:

import { one, two } from 'whatever';

// or

export { one, two } from 'whatever';

The result will then look like this:

[
  { path: 'whatever', identifiers: ['one', 'two'] }
]

instead of just this:

['whatever']

In the case of default exports like:

import foo from 'whatever';

We'll return:

{ path: 'whatever', identifiers: ['default'] }

In cases of import or re-export all, or dynamic imports, or where we otherwise just can't determine, like:

import * from 'whatever';

// or

export * from 'whatever';

// or

import('whatever').then(/* ... */);

We'll return:

{ path: 'whatever', identifiers: ['*'] }

[AndersDJohnson]

closing since upstream issue dependents/node-dependency-tree#147 was closed, to be replaced by #48 perhaps