Fix decompiled text for named companion object

Fix stub/ast mismatch for compiled named companion objects
Add tests

idea/testData/decompiler/decompiledText/ClassWithNamedClassObject.expected.kt

@@ -0,0 +1,11 @@
+// IntelliJ API Decompiler stub source generated from a class file
+// Implementation of methods is not available
+
+package test
+
+public final class ClassWithNamedClassObject public constructor() {
+    public companion object Named {
+        public final fun a(): kotlin.Unit { /* compiled code */ }
+    }
+}
+