[Issue #1853] Move where we define the lookup mapping to avoid constant import issues

[chouinar]

Summary

Fixes #1853

Time to review: 1 mins

Changes proposed

Move where we define the LookupConfig definitions to reduce circular dependencies

Context for reviewers

This doesn't change the configs, just where they're defined. We frequently want to import the enums defined in lookup_constants, but because that file in turn depends on the DB lookup files, we run into some odd circular dependencies that require manually sorting imports to resolve. Instead, we'll just define those LookupConfig classes in the only place they're ever used to avoid the headache.