JetDiagnosticsTest migrated to TestGenerator

- test data files renamed from *.jet to *.kt

compiler/testData/diagnostics/tests/scopes/kt1942.kt

@@ -0,0 +1,19 @@
+//FILE:a/C.java
+//KT-1942 Package local members from Java are visible in subclasses
+package a;
+
+public class C {
+    int myValue;
+}
+
+//FILE:d.kt
+
+package d
+
+import a.C
+
+class A : C() {
+    fun test() {
+        val <!UNUSED_VARIABLE!>v<!> = <!INVISIBLE_MEMBER!>myValue<!>
+    }
+}