1. Create a new class with a singleton architecture which saves the start of all URL's used in the code: https://api.production.wealthsimple.com/v1/
2. Allow with an internal access level to modify this start of the URL
3. Make sure that all entry point which call an URL will use the prefix

Rationale:
In future unit tests we will set this to our mock server and this way we can easily redirect all tests there