Create index files for each directory

[nicolesorial]

Problem: Because we use so many entities, controllers, and routes, it is tedious to work in files that need all of the entities because we need a new import for each one.

Solution: Create an index file that exports all entities and controllers (this is already done in the routes directory), and then change all the imports to import from the correct index file.

Specs:

• Export all entities in a new entity/index.ts file
• Export all controllers in a new controller/index.ts file
• In all files in entity, change imports to use directory/index.
• In all files in controller, change imports to use directory/index.
• In all files in seed_data/*, change imports to use directory/index.

Contact @nicolesorial if blocked or if you have questions!