Create a Bluetooth endpoint for Device inject connections. Will implement connection lifecycle callback for the inject connections in the following CL.

PiperOrigin-RevId: 430573921
diff --git a/connections/implementation/proto/offline_wire_formats.proto b/connections/implementation/proto/offline_wire_formats.proto
index a86c53d..7308ee9 100644
--- a/connections/implementation/proto/offline_wire_formats.proto
+++ b/connections/implementation/proto/offline_wire_formats.proto
@@ -89,6 +89,10 @@
   optional MediumMetadata medium_metadata = 7;
   optional int32 keep_alive_interval_millis = 8;
   optional int32 keep_alive_timeout_millis = 9;
+  // The type of {@link Device} object.
+  optional int32 device_type = 10 [default = 0];
+  // The bytes of serialized {@link Device} object.
+  optional bytes device_info = 11;
 }
 
 message ConnectionResponseFrame {