Dropping package facades:

- clashing JVM signature diagnostics should be reported in stable order
- drop tests for clashes vs package facades
- introduce box test for class named as old package facade
- fix some testData

compiler/testData/codegen/box/classes/classNamedAsOldPackageFacade.kt

@@ -0,0 +1,7 @@
+package test
+
+class TestPackage {
+    val OK = "OK"
+}
+
+fun box(): String = TestPackage().OK