Introduce KAnnotatedElement and val annotations: List<Annotation>

compiler/testData/codegen/boxWithStdlib/reflection/annotations/annotationRetentionAnnotation.kt

@@ -0,0 +1,15 @@
+import kotlin.test.assertEquals
+
+annotation(retention = AnnotationRetention.RUNTIME) class Anno
+
+fun box(): String {
+    val a = Anno::class.annotations
+/*
+    // TODO: support kotlin.annotation.annotation
+    if (a.size() != 1) return "Fail 1: $a"
+    val ann = a.single() as? annotation ?: return "Fail 2: ${a.single()}"
+    assertEquals(AnnotationRetention.RUNTIME, ann.retention)
+*/
+    assert(a.isEmpty())
+    return "OK"
+}