JetDiagnosticsTest migrated to TestGenerator

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

compiler/testData/diagnostics/tests/annotations/kt1860-positive.kt

@@ -0,0 +1,11 @@
+annotation class test {}
+
+fun foo(test <!UNUSED_PARAMETER!>f<!> : Int) {}
+
+var bar : Int = 1
+    set(test v) {}
+
+val x : (Int) -> Int = {([test] x : Int) -> x}
+
+class Hello(test args: Any) {
+}