Vector: Fix try_append (hopefully)

Still doesn't work with OwnedStringViews inside of structs.

luna/include/luna/Vector.h

@@ -78,7 +78,7 @@ template <typename T> class Vector
         resize(capacity).release_value();
     }
 
-    Result<void> try_append(T item)
+    Result<void> try_append(T&& item)
     {
         if (m_capacity == m_size) TRY(resize(m_capacity + 8));
 
@@ -89,6 +89,11 @@ template <typename T> class Vector
         return {};
     }
 
+    Result<void> try_append(const T& item)
+    {
+        return try_append(T(item));
+    }
+
     Option<T> try_pop()
     {
         if (m_size == 0) return {};