World size configuration

The WorldSize is a Resource so that I can use it in the entity wrapping
system. The size is pulled from a public constant in the config.rs file,
and the window is made that same size.

src/main.rs

@@ -1,10 +1,16 @@
-use bevy::prelude::*;
+use bevy::{prelude::*, window::WindowResolution};
 
-use asteroids::AsteroidPlugin;
+use asteroids::{config::WINDOW_SIZE, AsteroidPlugin};
 
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins)
+        .add_plugins(DefaultPlugins.set(WindowPlugin {
+            primary_window: Some(Window {
+                resolution: WindowResolution::new(WINDOW_SIZE.x, WINDOW_SIZE.y),
+                ..default()
+            }),
+            ..default()
+        }))
         .add_plugins(AsteroidPlugin)
         .run();
 }