Extend TypeSafetyPolicy tests to check supertype requests.

Create a new type Boss as a subtype of Person. Use this for a new test
in ExceptionThrowingTypeSafetyNeo4jTemplateTests. This makes all test of
the test class fail, showing that the type safety policy fails if the
requested type is a supertype of the stored type (e.g. stored is Boss,
but requested is the supertype Person). This is fixed through
DATAGRAPH-298, which changes the method
Neo4jEntityConverterImpl.storedAndRequestedTypesMatch to correctly check
for supertype.