Move all objects to object folders #397

I think it would make more sense if we stored all of the built in objects in object folders. (eg: object.json in a folder with any accompanying image files) I have a few reasons for this.

1. Presently, having nearly all of the built in objects as loose jsons has caused a lot of trouble among new object makers. As this repo is one of the main resources for people looking to make new objects. Especially those that only exist in OpenRCT2. So having the jsons loose teaches them bad habits that's just resulting in broken objects being sent out. I've already seen a fair number of people sharing unexportable jsons of climates/peep names or wondering why their .parkobj isn't getting read as the game only reads "object.json" from parkobj.
2. This would automatically build all of the built in objects as .parkobj, which would result in some minor but still nice file size reductions thanks to everything getting zip compression, instead of just the objects with images.
3. And lastly, this is pretty minor but it would make doing work on this repo a bit more consistent since every object would have the same structure. It would also make it easier to add new/replacement images to existing objects whenever original sprite fixes are needed.