JetDiagnosticsTest migrated to TestGenerator

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

compiler/testData/diagnostics/tests/regressions/kt588.kt

@@ -0,0 +1,13 @@
+// KT-588 Unresolved static method
+
+class Test() : Thread("Test") {
+    class object {
+        fun init2() {
+
+        }
+    }
+    override fun run() {
+        init2()      // unresolved
+        Test.init2() // ok
+    }
+}