Capacity degradation during startup

[jmaguire1]

We should be tracking how it takes a few minutes to AC/ASHPs (and also HPWHs) to reach the full capacity when the HP starts up. This will be useful when running at short timesteps to account for how we go from cold to a warmed up steady state. With short timesteps, these transients can matter, and we'll get more realistic results for those first few minutes (up to 5) and more realistically account for how cycling degrades performance.

[jmaguire1]

Close via #180.

Technically HPWHs have startup capacity degradation as well, but I'm not convinced we need to worry about it. It's way harder to work out what the time to steady state is for HPWHs because of the heat going into a tank, and also less important to account for it for the same reason. It's really rare to see cycles short enough that these losses have a big impact on cycle length like they do for HVAC.