feat #1  bridge fixes and tests implementation

bridge modification in order to be consistent with the specification and tests implementation.
The tests aim to verify the behavior of atlas widget used through the bridge and the data binding in both directions (from atlas to hsp and vice-versa).
Close #1
We now support a new template definition syntax that you should use

```cs
{export template atlas using c:WidgetBridgeCtrl}
...
{/template}
```