Add document factory base class backed by Map and Lambda functional object

Implement a new document factory base class (MappedDocumentFactory class and IMappedDocumentFactory interface).

Example Usage:

With following Doc class.

Developer can use one of the following approach:

1. At plugin Activator start method, register the document class.

2. Create an osgi component, at the bind method for the IMappedDocumentFactory service.

3. Create a subclass of MappedDocumentFactory, register as IDocFactory service (DO NOT register as IMappedDocumentFactory service).