Support dot notation to define the datasource value and content for Select/Radio/List controls

As a screen designer I would like to setup the datasource properties (value, content) using dot notation so I can use properties from different levels of the datasource. Ex.
For this data source structure:
```
{
  id:34,
  attributes:{
    name: "window",
    size: {
      width: 100,
      height: 50
    }
  }
}
```
Configure:
value: `id`
content: `attributes.name`
