Add world.quit function

src/world.zig

@@ -47,6 +47,10 @@ pub fn World(comptime ctx: anytype) type {
             return c.ecs_progress(self.raw, delta_time);
         }
 
+        pub fn quit(self: *Self) void {
+            c.ecs_quit(self.raw);
+        }
+
         /// Returns an `Entity` for the specified `ecs_entity_t` value, or an
         /// error if the entity is invalid or not alive in this `World`.
         pub fn lookupAlive(self: *Self, id: c.ecs_entity_t) !Entity(ctx) {