Add add-on modules to sys.modules

[amontanez24]

Problem Description

As a user, it would be useful if importing for premium features worked the same as for public features.

Expected behavior

For some premium features, we want to add modules that don't exist and be able to import from them.

from sdv.new_module import NewClass

Currently this is not supported. To fix this, we need to add the new modules to sys.modules, since that is the dict python uses for imports.