Games mixed with two settings files

[ptaillandier]

Describe the bug
When I want to run the "Simple Toolchain/Demos/Single-player game", the middleware mixes it with the default game "LinkToUnity"

To Reproduce
Steps to reproduce the behavior:

1. in the .env file, add a link to the GAMA SIMPLE plugin for the EXTRA_LEARNING_PACKAGE_PATH (e.g. : EXTRA_LEARNING_PACKAGE_PATH="/Users/patricktaillandier/Documents/GitHub/simple.toolchain/GAMA Plugin/gaml.extension.unity/models/LinkToUnity")
2. Run the middleware, choose "Simple Toolchain/Demos/Single-player game"
3. The game is waiting for 4 players, whereas it is specified in the setting.json of "Simple Toolchain/Demos/Single-player game" just 1 player. The "4 players" thing comes from the settings "LinkToUnity"
   {
   "type": "json_settings",
   "name": "LinkToUnity",
   "splashscreen": "learning-packages/demo/splashscreen/demoOne.png",
   "model_file_path": "./Models/Demo/Simple Player Game/DemoModelVR.gaml",
   "experiment_name": "vr_xp",
   "minimal_players": "0",
   "maximal_players": "4",
   "selected_monitoring": "gama_screen"
   }

Expected behavior
Just waiting one player for "Simple Toolchain/Demos/Single-player game"

[GuillaumeLeroy34]

While trying to fix this bug, I noted that the model stated fails to compile. This is not directly tied to the issue, but a system in the web platform that is able to show that a model failed to launch is needed for better feedback. Right now, the user may be stuck on an endlessly loading page, either if no response is given, or if the GAMA server responds with an error.

[GuillaumeLeroy34]

Should be fixed on branch dev