Wrap get_reader declaration for readability

Reformat the get_reader method declaration in EntryImpl to split the parameter list across lines and align the Environment* env parameter. This is a non-functional style change to improve readability and comply with line-length/coding-style preferences.

Author: jimmywarting

src/dataqueue/queue.cc

@@ -33,7 +33,8 @@ class NonIdempotentDataQueueReader;
 
 class EntryImpl : public DataQueue::Entry {
  public:
-  std::shared_ptr<DataQueue::Reader> get_reader(Environment* env = nullptr) override = 0;
+  std::shared_ptr<DataQueue::Reader> get_reader(
+      Environment* env = nullptr) override = 0;
 };
 
 class DataQueueImpl final : public DataQueue,