Make Fuel a required component on machines

It will be pulled in automatically by Bevy, now. I've also set a default
fuel level of 5 units.

src/game/mod.rs

@@ -16,16 +16,22 @@ pub mod machines {
 
   use bevy::prelude::*;
 
+  use crate::game::consumables::Fuel;
+
   #[derive(Component)]
+  #[require(Fuel)]
   pub struct CuttingMachine;
 
   #[derive(Component)]
+  #[require(Fuel)]
   pub struct RotatingMachine;
 
   #[derive(Component)]
+  #[require(Fuel)]
   pub struct FlippingMachine;
 
   #[derive(Component)]
+  #[require(Fuel)]
   pub struct TransposingMachine;
 }
 
@@ -35,6 +41,11 @@ pub mod consumables {
   #[derive(Component)]
   pub struct Fuel(pub u32);
 
+  impl Default for Fuel {
+    fn default() -> Self {
+        Self(5)
+    }
+  }
   #[derive(Event)]
   pub struct FuelChanged;
 }