Adds an interface for GetUserInfo, which gets corso-specific metadata for a single user. Also does some refactoring around discovery for better interface consistency, both as variables and as access layers. --- #### Does this PR need a docs update or release note? - [x] ⛔ No #### Type of change - [x] 🌻 Feature #### Test Plan - [x] ⚡ Unit test - [x] 💚 E2E