IR: copy annotations when making lateinit fields nullable

compiler/testData/codegen/box/annotations/annotationsOnLateinitFields.kt

@@ -0,0 +1,15 @@
+// WITH_REFLECT
+// TARGET_BACKEND: JVM
+
+@Target(AnnotationTarget.FIELD)
+annotation class Ann
+
+class C {
+    @Ann
+    lateinit var x0: String
+}
+
+fun box(): String {
+    require(C::class.java.getDeclaredField("x0")?.getAnnotation(Ann::class.java) != null)
+    return "OK"
+}