When the current API test suite was first implemented, we had test

suites populate their objects and return some state in

setup_basic_<httpmethod>_test() methods. That state was returned as

tuples, making it hard to expand upon this.
Now that we have dictionaries that store state for an API test, it's

time to gradually move away from these methods. Subclasses can now

define an equivalent populate_*_test_objects() method, which takes in

the setup_state and some parameters for controlling the population,

and then updates setup_state with the new data. This ensures

everything is stored in one place, and gives us room for expansion.
New keys were added to setup_state for upcoming test changes. This

includes:

auth_user: The logged-in user.
with_local_site: Whether testing is done on a Local Site.
local_site: The instance of the Local Site.
local_site_name: The name of the Local Site.
local_sites_in_db: Whether there are Local Sites in the database.
owner: The user owning objects being modified/deleted in a test.

  This may differ from auth_user, and replaces user.
test_objects: Arbitrary key/value storage for tests, used for

  upcoming comparison and query assertion support.

And authentication state has been fixed when trying to log in with an

explicit user who is not already logged in.
This test restructuring is necessary for getting us to the point of

having standardized query assertions, to help work toward peak API

performance.

Unit tests pass.
Made use of all the new functionality in the upcoming API query

assertion code.