Split `populate_component_properties` into separate properties/methods

[jessegrabowski]

The PyMCStateSpace class asks the user to fill out an (admittedly) huge number of properties so the model can build the coords/dims:

• param_names
• data_names
• param_info
• data_info
• state_names
• observed_states
• shock_names
• coords
• param_dims

I get confused by these and I wrote the thing, so clearly others don't have much hope. So we should think about a better way to organize all this information.

This issue isn't about that, though. When I originally wrote the Component class, I thought "all these properties are horrible, let's gather everything into one place". Thus populate_component_properties was born. This class is somehow even more confusing to look at than the list of properties. Everything is mixed together in one place, and it's not obvious what is required.

I think the individual properties is a better approach -- at minimum, it's consistent with the PyMCStateSpace class, and it's easier to look at and read.