Add RemoteDeviceLoader to create RemoteDevice from CryptAuth data.

components/proximity_auth/remote_device.h

Index: components/proximity_auth/remote_device.h
diff --git a/components/proximity_auth/remote_device.h b/components/proximity_auth/remote_device.h
index 582f2f730f264ae24ecb936f2d737f1ba37138bc..38cc56847555f09e219f60aee00840c3d00d508b 100644
--- a/components/proximity_auth/remote_device.h
+++ b/components/proximity_auth/remote_device.h
@@ -11,16 +11,24 @@ namespace proximity_auth {
 
 struct RemoteDevice {
  public:
+  enum BluetoothType { BLUETOOTH_CLASSIC, BLUETOOTH_LE };
+
+  std::string user_id;
   std::string name;
   std::string public_key;
+  BluetoothType bluetooth_type;
   std::string bluetooth_address;
   std::string persistent_symmetric_key;
+  std::string sign_in_challenge;
 
   RemoteDevice();
-  RemoteDevice(const std::string& name,
+  RemoteDevice(const std::string& user_id,
+               const std::string& name,
                const std::string& public_key,
+               BluetoothType bluetooth_type,
                const std::string& bluetooth_address,
-               const std::string& persistent_symmetric_key);
+               const std::string& persistent_symmetric_key,
+               std::string sign_in_challenge);
   ~RemoteDevice();
 };