Move SpawnAsteroid event into events.rs

src/events.rs

@@ -1,5 +1,7 @@
 use bevy::prelude::*;
 
+use crate::asteroids::AsteroidSize;
+
 /// Signals that the player's ship has been destroyed.
 /// Used when the player collides with an asteroid.
 #[derive(Event)]
@@ -10,6 +12,13 @@ pub(crate) struct ShipDestroy;
 #[derive(Event)]
 pub(crate) struct AsteroidDestroy(pub Entity);
 
+#[derive(Event)]
+pub struct SpawnAsteroid {
+    pub pos: Vec2,
+    pub vel: Vec2,
+    pub size: AsteroidSize,
+}
+
 // TODO: BulletDestroy
 // Which depends on the still-pending Bullet component creation.