Move heal locations data to their associated map.json

[GriffinRichards]

The data that was in src/data/heal_locations.h is now distributed across map.json files, and mapjson will use that data to automatically generate heal_locations.h.

The primary reason for this change is that currently Porymap overwrites heal_locations.h, which means that users are very limited in what they can do with heal location data. Now that mapjson has that responsibility the heal location C data can be formatted arbitrarily.

There are a few smaller benefits as well. For one, the data for each heal location is neatly collected in one object, rather than spread across 3 different arrays. The respawn_map and respawn_npc fields are also much closer now to their corresponding warp and object event, so it should be much easier to notice when one of them needs to be updated.

From a build process standpoint it would be easier to put this data in a single combined heal_locations.json file, but I think this loses out on the organizational benefits above.