Add solution for "Day 2: Gift Shop", part 1

tests/examples.rs

@@ -16,6 +16,14 @@ fn secret_entrance() {
     );
 }
 
+#[test]
+fn gift_shop() {
+    assert_eq!(
+        Ok((1227775554, 0)),
+        solvers::run_solver(solvers::gift_shop::GiftShop {}, &EXAMPLE_PATHS)
+    );
+}
+
 #[test]
 fn printing_department() {
     assert_eq!(

tests/full_data.rs

@@ -11,6 +11,14 @@ fn secret_entrance() {
     );
 }
 
+#[test]
+fn gift_shop() {
+    assert_eq!(
+        Ok((38158151648, 0)),
+        solvers::run_solver(solvers::gift_shop::GiftShop {}, &solvers::DATA_PATHS)
+    );
+}
+
 #[test]
 fn printing_department() {
     assert_eq!(