Big change in quickfix tests: no stupid test data format with "before" and "after" file prefixes

idea/testData/quickfix/suppress/declarationKinds/classObject.kt

@@ -0,0 +1,7 @@
+// "Suppress 'REDUNDANT_NULLABLE' for companion object Companion of C" "true"
+
+class C {
+    companion object {
+        var foo: String?<caret>? = null
+    }
+}