JetDiagnosticsTest migrated to TestGenerator

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

compiler/testData/diagnostics/tests/regressions/kt443.kt

@@ -0,0 +1,14 @@
+// KT-443 Write allowed to super.val
+
+open class M() {
+    open val b: Int = 5
+}
+
+class N() : M() {
+    val a : Int
+        get() {
+            <!VAL_REASSIGNMENT!>super.b<!> = super.b + 1
+            return super.b + 1
+        }
+    override val b: Int = a + 1
+}