Dot-notation not supported in nested keys

The purpose of dot-notation is to support nesting, yet dot-notation is not supported in nested keys. Example:
```javascript
dataLayer.push({ a: { 'b.c': 1 } }); 
dataLayerHelper.get( 'a' );     // {'b.c':1} ❌ Expected: { b: { c: 1 } }
dataLayerHelper.get( 'a.b' );   // undefined ❌ Expected: { c: 1 }
dataLayerHelper.get( 'a.b.c' ); // undefined ❌ Expected: 1
```