PY-84469 Consider ClassVar when matching protocol and a concrete class

(cherry picked from commit 76af969cfe9318049f02dc7f6bdd03fe20a9504f)

IJ-MR-174248

GitOrigin-RevId: b34de32baf939e812169976761acd41eaa8aba38

python/python-psi-api/src/com/jetbrains/python/codeInsight/PyCustomMember.java

@@ -38,6 +38,8 @@ public class PyCustomMember extends UserDataHolderBase {
   private final PsiElement myTarget;
   private PyPsiPath myPsiPath;
 
+  private boolean myIsClassVar = false;
+
   boolean myFunction = false;
 
   /**
@@ -243,6 +245,16 @@ public class PyCustomMember extends UserDataHolderBase {
     return myFunction;
   }
 
+
+  public PyCustomMember asClassVar() {
+    myIsClassVar = true;
+    return this;
+  }
+
+  public boolean isClassVar() {
+    return myIsClassVar;
+  }
+
   /**
    * Checks if some reference points to this element
    *