The network controller is now constructed within each network
controller unit test, rather than in the `beforeEach`. This allows us
to customize the constructor options in each test, which some planned
future tests will require.
The controller is constructed with a helper function that also handles
calling `destroy` after each test, even if the test failed. This helps
to prevent tests from affecting each other.
Co-authored-by: Elliot Winkler <elliot.winkler@gmail.com>