JetDiagnosticsTest migrated to TestGenerator

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

compiler/testData/diagnostics/tests/scopes/kt1580.kt

@@ -0,0 +1,15 @@
+//FILE:a.kt
+//KT-1580 Can't access nested class/trait from other package
+package lib
+trait WithInner {
+    trait Inner {
+    }
+}
+
+//FILE:b.kt
+package user
+
+import lib.WithInner
+
+fun main(<!UNUSED_PARAMETER!>a<!> : WithInner, <!UNUSED_PARAMETER!>b<!> : WithInner.Inner) {
+}