RAII for auto-closing file streams

Small fixes I didn't want to include in unrelated PRs.

There are a few left in `storage.cpp` but since it's a single function
in 600 lines of code, I didn't want to touch the mess. The others are
safe to remove, cucumber and test run on Finland gives 👍.

src/storage/storage.cpp

@@ -288,7 +288,6 @@ int Storage::Run()
         else
         {
             getline(timestamp_stream, m_timestamp);
-            timestamp_stream.close();
         }
     }
     if (m_timestamp.empty())