Support Kotlin annotation constructors in reflection

#KT-13106 In Progress

compiler/testData/codegen/box/reflection/constructors/annotationClass.kt

@@ -0,0 +1,21 @@
+// WITH_REFLECT
+
+import kotlin.reflect.*
+import kotlin.test.assertEquals
+
+annotation class A1
+
+annotation class A2(val k: KClass<*>, val s: A1)
+
+fun box(): String {
+    assertEquals(1, A1::class.constructors.size)
+    assertEquals(A1::class.primaryConstructor, A1::class.constructors.single())
+
+    val cs = A2::class.constructors
+    assertEquals(1, cs.size)
+    assertEquals(A2::class.primaryConstructor, cs.single())
+    val params = cs.single().parameters
+    assertEquals(listOf("k", "s"), params.map { it.name })
+
+    return "OK"
+}

compiler/testData/codegen/box/reflection/constructors/classesWithoutConstructors.kt

@@ -1,10 +1,8 @@
 // WITH_REFLECT
 
-import kotlin.reflect.*
 import kotlin.test.assertTrue
 
 interface Interface
-annotation class Anno(val x: Int)
 object Obj
 
 class C {
@@ -13,7 +11,6 @@ class C {
 
 fun box(): String {
     assertTrue(Interface::class.constructors.isEmpty())
-    assertTrue(Anno::class.constructors.isEmpty())
     assertTrue(Obj::class.constructors.isEmpty())
     assertTrue(C.Companion::class.constructors.isEmpty())