Add a unit test utility function for creating users.

Review Request #10649 — Created July 26, 2019 and submitted — Latest diff uploaded

Information

Review Board
release-3.0.x
7343ef4...

Reviewers

This introduces a create_user() function for test suites that
simplifies creating users with some default data, and makes it easier to
add permissions for a user (which normally requires some annoying
queries).

Over time, this will reduce the need for the test_users fixture,
generally speeding up tests.

Used this successfully in an upcoming change.