Implement a pathway to include .ies files in the model.to.rad_folder method

[chriswmackey]

This is a necessary pre-step to support the use of .ies files in Point-In-Time recipes. I can see that there's already a folder to store ies files in the radiance folder structure:

https://github.com/ladybug-tools/radiance-folder-structure/tree/master/radiance_folder/model

So I think we just need some objects to store Luminaire data, which can them be assigned to the model.

[mostaphaRoudsari]

cc: @chriswmackey and @mikkelkp

[toshtaar]

@chriswmackey could please give a hint on how to include a *.rad file during simulation with PIT View based method?