Simulation Result temperature tests

There currently appears to be no test that runs a simulation and verifies the numerical value of shaded/unshaded up/down temperatures.

To get the base case, use settings as per `TEST_SIMULATION_RESULT` in `test_simulate.py`, and make a note of the sum of the up and down shaded/unshaded temps.

In `test_simulate.py`, use `TEST_SIMULATION_RESULT` and assert that the sum of these properties is as noted above. Use pytest.approx.