Switch ResourceHandle to use StringRef when storing container, name, and device strings (NFC).

These are never created and instead are referencing attributes from an op.

PiperOrigin-RevId: 345028070
Change-Id: Iea40d9ac930214c328746e59283b8ba90b249a2e

Author: andyly

tensorflow/compiler/mlir/tensorflow/ir/tf_op_interfaces.h

@@ -82,9 +82,9 @@ struct ResourceHandle {
   // Make ResourceHandle hashable.
   friend ::llvm::hash_code hash_value(const ResourceHandle& resource_handle);
 
-  std::string container;
-  std::string name;
-  std::string device;
+  StringRef container;
+  StringRef name;
+  StringRef device;
   Operation* op = nullptr;
 };