evaluate types in terms of the class in which they appear

evaluate types in terms of the class in which they appear

Fixed issues within the declarative typing resolver (i.e. which resolves
``ForwardRef`` objects) where types that were declared for columns in one
particular source file would raise ``NameError`` when the ultimate mapped
class were in another source file.  The types are now resolved in terms
of the module for each class in which the types are used.

Fixes: #8742
Change-Id: I236f94484ea79d47392a6201e671eeb89c305fd8