Refactor: Add a 'domain' folder

[TangoYankee]

Description

The controllers, services, and repositories are organized into "domain" folders. However, these folders are direct siblings with other utility folders, such as "pipes", "filter", and "exception". This can make it difficult to tell at a glance which folders constitute domains. Moving these folders into a "domain" folder should add clarity.

Acceptance criteria

• A "domain" folder is created as a child of "src"
• Folders that constitute a "domain" are moved to that folder
  • borough
  • land-use
  • tax-lot
  • zoning-district
  • zoning-district-class