JSON subdivision

[Srykah]

JSON files each contain all their respective data (for example, the JSON file for the attacks contains ALL the attacks in the game) ; they should be broken into one file per data item (so, in an attacks folder, have a different JSON file for each attack and so on)

This will help readability, ease of contributing and loading times if we ever want to multithread it one day ^^

[TelloViz]

This goes along with what I was thinking about the map.json file.

• One map per file

• A table of contents sort of file containing a list of maps (I'm not sure how JSON works..?)

[Srykah]

With the help of std::filesystem we don't even need a table of contents ^^

[milkyroute]

I fixed this with #164 for the maps, we'll see if we split other things but it won't be a problem in the code so I consider this issue fixed.