Closed, Acceptance tests pass
The ContentSelectorDialog and Search is refactored to work with AllowedTypesAttribute.
Any restricted type/class for the property type of ContentReference/PageReference/BlockReference etc. will be dimmed out in the ContentSelectorDialgor for that property. This will help editor to figure out that certain types are not allowed to select for the given property.
In the same way, if editor opens the ContentSelector for that property and search a content, the restricted type/class will not appear in search results.