Dummy ship, single input, and motion integrator

The ship, such as it is, exists and moves when the player presses "W".

Position is updated according to velocity, and the mesh transform is
updated to match the position.

src/main.rs

@@ -0,0 +1,10 @@
+use bevy::prelude::*;
+
+use asteroids::AsteroidPlugin;
+
+fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .add_plugins(AsteroidPlugin)
+        .run();
+}