Element Class Does Not Expose QualifiedName Or SourceUri

[JeffFerguson]

The Element class should expose the following read-only properties for enhanced schema element display information to consumers:

• SourceUri: The Element class should support a property called SourceUri, which returns the URI of the schema in which the element was defined. This information may differ from the parent schema's LoadPath property, especially if the element was defined in a schema imported with an <import> directive.
• QualifiedName: Currently, the Element class supports a property called Name, which returns the local name of an element. However, since Name is a string, it does not return the fully-qualified name of the element, which also contains the element's namespace information. In addition to the Name property, which should be retained, the Element class should support a property called QualifiedName, of type QualifiedName. This property will expose both the element's local name and namespace, allowing the name's namespace information to be made available to consumers.