[FIX] frame_id for depth camera point cloud in Fortress

Fixes #239 and husarion/rosbot_ros#55 for Gazebo Fortress

## Summary

Using `ignition_frame_id` did not change the frame id in the depth camera point cloud message.

With this fix, the depth camera point cloud message's frame id will be updated according to the set `ignition_frame_id`.

Signed-off-by: Keith Valentin <[email protected]>

src/DepthCameraSensor.cc

@@ -309,10 +309,13 @@ bool DepthCameraSensor::Load(const sdf::Sensor &_sdf)
   // the xyz and rgb fields to be aligned to memory boundaries. This is need
   // by ROS1: https://github.com/ros/common_msgs/pull/77. Ideally, memory
   // alignment should be configured.
-  msgs::InitPointCloudPacked(this->dataPtr->pointMsg, this->FrameId(), true,
+  msgs::InitPointCloudPacked(
+      this->dataPtr->pointMsg,
+      this->OpticalFrameId(),
+      true,
       {{"xyz", msgs::PointCloudPacked::Field::FLOAT32},
        {"rgb", msgs::PointCloudPacked::Field::FLOAT32}});
-
+  
   if (this->Scene())
   {
     this->CreateCamera();
@@ -554,9 +557,10 @@ bool DepthCameraSensor::Update(
                rendering::PF_FLOAT32_R));
   msg.set_pixel_format_type(msgsFormat);
   *msg.mutable_header()->mutable_stamp() = msgs::Convert(_now);
+
   auto frame = msg.mutable_header()->add_data();
   frame->set_key("frame_id");
-  frame->add_value(this->FrameId());
+  frame->add_value(this->OpticalFrameId());
 
   std::lock_guard<std::mutex> lock(this->dataPtr->mutex);
   msg.set_data(this->dataPtr->depthBuffer,