Combine Cases Macro doesn't check simulation timesteps

[brtietz]

Describe the bug

The combine cases macro will gleefully combine cases with different weather file timesteps, leading to odd phenomena like PV generating at night.

To Reproduce

Steps to reproduce the behavior:

1. Set up a SAM case with two PV cases and a generic system
2. Give one PV case an hourly weather file, and another case a subhourly file
3. Set up a generic system to combine the cases, and run
4. See PV generating at night!

Expected behavior

The combine cases macro should at least throw an error if a user tries to do this, or maybe if we have lots of time interpolate to a consistent timestep.

[janinefreeman]

Official vote to describe more of our bugs as "gleeful"! 😝