extract to file, primitive player system that is not actually run

src/game.rs

@@ -0,0 +1,9 @@
+use bevy::prelude::*;
+use bevy_rapier2d::prelude::*;
+use player::player_plugin;
+
+mod player;
+
+fn game_plugin(app: &mut App) {
+    app.add_plugins((player_plugin));
+}