This essentially fixes one bug surrounding the case for fetching or updating user info, but in the process this change:

• Refactors SDK to use classical inheritance in order to make its structure clearer and easier to understand
• Adds test mocks for reliable and repeatable runs
• Enables infinite retries when fetching app configs just in case of network/infra issues
• Waits for app config to load when attempting to fetch user profile info, but doesn't wait forever