Add ability to load different label to current image

Describe the solution you'd like
clicking next image would load 'orignal' label when that setting is enabled. If would be nice to have a user select the tag in the active learning strategy options, then slicer would only call server to get the label with that tag.

Describe alternatives you've considered
I managed to get it to work after modifying slicer code. It may be a bit hacky as I assume a cmd name in the strategy to skip calling the main image

    def onNextSampleButton(self):
        if not self.logic:
            return
            
        curr_image_id = self.ui.inputSelector.currentText  # aeh avoid unneeded reload 
        curr_image_id = curr_image_id[:curr_image_id.find(".nii")] if curr_image_id else ""
        print(f"========{curr_image_id}")

        loadNewImage=True
        try:  ## moved code up  duplicate to check command and keep same image 
            # qt.QApplication.setOverrideCursor(qt.Qt.WaitCursor)
            #self.updateServerSettings()
            strategy = self.ui.strategyBox.currentText
            if not strategy:
                slicer.util.errorDisplay("No Strategy Found/Selected\t")
                return
            strategyParams=self.getParamsFromConfig("activelearning", strategy)
            label_tag2get = strategyParams.get('label_tag',"original")
            cmd=strategyParams.get("cmd", None)
            if cmd=="LoadLabelTag" and len(curr_image_id)>0:
                loadNewImage=False
        except BaseException as e:
            msg = f" aeh new code Message:: {e.msg}" if hasattr(e, "msg") else ""
            slicer.util.errorDisplay(
                f"Failed to fetch Sample from MONAI Label Server.\n{msg}",
                detailedText=traceback.format_exc(),
            )
        print(f"========{curr_image_id} {loadNewImage=}")
        
        if loadNewImage and (self._volumeNode or len(slicer.util.getNodesByClass("vtkMRMLScalarVolumeNode")) ):
            if not slicer.util.confirmOkCancelDisplay(
                "This will close current scene.  Please make sure you have saved your current work.\n"
                "Are you sure to continue?"
            ):
                return
            self.onResetScribbles()
            slicer.mrmlScene.Clear(0)

        start = time.time()
        try:
            qt.QApplication.setOverrideCursor(qt.Qt.WaitCursor)

            self.updateServerSettings()
            #strategy = self.ui.strategyBox.currentText  # moved up 
            #if not strategy:
            #    slicer.util.errorDisplay("No Strategy Found/Selected\t")
            #    return
 
            #strategyParams=self.getParamsFromConfig("activelearning", strategy)  #moved up
            #strategyParams["current_loaded_image_id"] = curr_image_id ## will use this id when asking to compare models 

            if not loadNewImage: #aeh avoid un needed reload 
                image_id = curr_image_id
                print(f" keeping same sample {image_id}")
            else:                    

                sample = self.logic.next_sample(strategy, strategyParams )
                logging.debug(sample)
                if not sample.get("id"):
                    slicer.util.warningDisplay(
                        "Unlabled Samples/Images Not Found at server.  Instead you can load your own image."
                    )
                    return

                if loadNewImage and self.samples.get(sample["id"]) is not None:
                    self.current_sample = self.samples[sample["id"]]
                    name = self.current_sample["VolumeNodeName"]
                    index = self.ui.inputSelector.findText(name)
                    self.ui.inputSelector.setCurrentIndex(index)
                    return

                logging.info(sample)
                image_id = sample["id"]
                image_file = sample.get("path")
                image_name = sample.get("name", image_id)
                node_name = sample.get("PatientID", sample.get("name", image_id))
                checksum = sample.get("checksum")
                local_exists = image_file and os.path.exists(image_file)
                
                print(f"------- aeh next sample id is {image_id} labeltag= {label_tag2get} ")
                logging.info(f"Check if file exists/shared locally: {image_file} => {local_exists}")
                if local_exists:
                    self._volumeNode = slicer.util.loadVolume(image_file)
                    self._volumeNode.SetName(node_name)
                else:
                    download_uri = f"{self.serverUrl()}/datastore/image?image={quote_plus(image_id)}"
                    logging.info(download_uri)

                    sampleDataLogic = SampleData.SampleDataLogic()
                    self._volumeNode = sampleDataLogic.downloadFromURL(
                        nodeNames=node_name, fileNames=image_name, uris=download_uri, checksums=checksum
                    )[0]

            if slicer.util.settingsValue("MONAILabel/originalLabel", True, converter=slicer.util.toBool):
                try:
                    datastore = self.logic.datastore()
                    label_info = datastore["objects"][image_id]["labels"][label_tag2get]["info"]
                    labels = label_info.get("params", {}).get("label_names", {})

                    if labels:
                        # labels are available in original label info
                        labels = labels.keys()
                    else:
                        # labels not available
                        # assume labels in app info are valid for original label file
                        labels = self.logic.info().get("labels")

                    # ext = datastore['objects'][image_id]['labels']['original']['ext']
                    maskFile = self.logic.download_label(image_id, label_tag2get)
                    self.updateSegmentationMask(maskFile, list(labels))   ## aeh copied above
                    print(f"label tag {label_tag2get} label loaded! ")
                except:
                    print(f"label tag {label_tag2get} label not found /errors ... ")
            
            if loadNewImage: ## aeh added condition
                self.initSample(sample)

        except BaseException as e:
            msg = f"Message:: {e.msg}" if hasattr(e, "msg") else ""
            slicer.util.errorDisplay(f"Failed to fetch Sample from MONAI Label Server.\n{msg}",detailedText=traceback.format_exc(), )
        finally:
            qt.QApplication.restoreOverrideCursor()

        self.updateGUIFromParameterNode()
        logging.info(f"Time consumed by next_sample: {time.time() - start:3.1f}")

Start at the Slicer-side onNextSampleButton entry point and trace its calls to next_sample, datastore, download_label, and updateSegmentationMask. Review how active-learning strategy parameters are read, then make selecting a label tag load that tag without unnecessarily reloading the current image. Done means the selected tag is loaded when advancing images and the existing image-loading behavior still works.