introduce RawSignatureItem to transfer html description via rd protocol

platform/lang-impl/src/com/intellij/codeInsight/hint/ParameterInfoComponent.java

@@ -246,6 +246,11 @@ public class ParameterInfoComponent extends JPanel {
 
     @Override
     public void setupRawUIComponentPresentation(String htmlText) {
+      ParameterInfoController.RawSignatureItem item = new ParameterInfoController.RawSignatureItem(htmlText);
+
+      result.current = getCurrentParameterIndex();
+      result.signatures.add(item);
+
       myPanels[i].setup(htmlText, getDefaultParameterColor());
       myPanels[i].setBorder(isLastParameterOwner() || isSingleParameterInfo() ? EMPTY_BORDER : BOTTOM_BORDER);
     }

platform/lang-impl/src/com/intellij/codeInsight/hint/ParameterInfoController.java

@@ -715,7 +715,18 @@ public class ParameterInfoController extends UserDataHolderBase implements Visib
     }
   }
 
-  public static class SignatureItem {
+  public interface SignatureItemModel {
+  }
+
+  public static class RawSignatureItem implements SignatureItemModel {
+    public final String htmlText;
+
+    RawSignatureItem(String htmlText) {
+      this.htmlText = htmlText;
+    }
+  }
+
+  public static class SignatureItem implements SignatureItemModel {
     public final String text;
     public final boolean deprecated;
     public final boolean disabled;
@@ -736,7 +747,7 @@ public class ParameterInfoController extends UserDataHolderBase implements Visib
   }
 
   public static class Model {
-    public final List<SignatureItem> signatures = new ArrayList<>();
+    public final List<SignatureItemModel> signatures = new ArrayList<>();
     public int current = -1;
     public TextRange range;
     public Editor editor;