provide stub implementation for model search (IDEA-CR-61813)

GitOrigin-RevId: 62adeb0c5d4db401ee48047f837bd23cd330bc32

platform/indexing-impl/src/com/intellij/psi/impl/search/WordRequestInfoImpl.kt

@@ -23,6 +23,6 @@ internal data class WordRequestInfoImpl internal constructor(
   override fun getContainerName(): String? = containerName
 
   override fun getSearchSession(): SearchSession {
-    TODO("not implemented")
+    return SearchSession() // layered searches optimization is not applicable to model search, continue to search the old way
   }
 }