test: rework lib stuff to share common files

test/lib/registry/shared/lib.cpp

@@ -0,0 +1,19 @@
+#include <entt/core/attribute.h>
+#include <entt/entity/registry.hpp>
+#include "types.h"
+
+ENTT_API void update_position(entt::registry &registry) {
+    registry.view<position, velocity>().each([](auto &pos, auto &vel) {
+        pos.x += static_cast<int>(16 * vel.dx);
+        pos.y += static_cast<int>(16 * vel.dy);
+    });
+}
+
+ENTT_API void emplace_velocity(entt::registry &registry) {
+    // forces the creation of the pool for the velocity component
+    static_cast<void>(registry.storage<velocity>());
+
+    for(auto entity: registry.view<position>()) {
+        registry.emplace<velocity>(entity, 1., 1.);
+    }
+}