JetDiagnosticsTest migrated to TestGenerator

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

compiler/testData/diagnostics/tests/regressions/kt26.kt

@@ -0,0 +1,12 @@
+// FILE: a.kt
+// KT-26 Import namespaces defined in this file
+
+import html.* // Must not be an error
+
+// FILE: b.kt
+
+package html
+
+abstract class Factory<T> {
+fun create() : T? = null
+}