[VISUALIZER] Replace rendering of class with no name to anonymous

compiler/visualizer/testData/rawBuilder/declarations/emptyAnonymousObject.kt

@@ -1,6 +1,6 @@
 // FIR_IGNORE
 fun test() {
-//      test.<no name provided>
+//      <anonymous>
 //      │
     val x = object {}
 }

compiler/visualizer/testData/rawBuilder/expressions/locals.kt

@@ -31,7 +31,7 @@ fun withLocals(p: Int): Int {
 //                │ fun (Any).hashCode(): Int
 //                │ │
         fun foo() = hashCode()
-//     fun (withLocals.<no name provided>).foo(): Int
+//     fun (<anonymous>).foo(): Int
 //     │
     }).foo()