Generate separate anonymous class for each property reference

Each property reference obtained by the '::' operator now causes back-end to
generate an anonymous subclass of the corresponding KProperty class, with the
customized behavior. This fixes a number of issues:

- get/set/name of property references now works without kotlin-reflect.jar in
  the classpath
- get/set/name methods are now overridden with statically-generated property
  access instead of the default KPropertyImpl's behavior of using Java
  reflection, which should be a lot faster
- references to private/protected properties now work without the need to set
  'accessible' flag, because corresponding synthetic accessors are generated at
  compile-time near the target property

 #KT-6870 Fixed
 #KT-6873 Fixed
 #KT-7033 Fixed

compiler/testData/codegen/boxWithStdlib/callableReference/property/kt6870_privatePropertyReference.kt

@@ -0,0 +1,22 @@
+class Test {
+    private var iv = 1
+
+    public fun exec() {
+        val t = object : Thread() {
+            override fun run() {
+                ::iv.get(this@Test)
+                ::iv.set(this@Test, 2)
+            }
+        }
+        t.start()
+        t.join(1000)
+    }
+
+    fun result() = if (iv == 2) "OK" else "Fail $iv"
+}
+
+fun box(): String {
+    val t = Test()
+    t.exec()
+    return t.result()
+}

compiler/testData/codegen/boxWithStdlib/reflection/properties/privateClassVal.kt

@@ -5,7 +5,7 @@ import kotlin.reflect.jvm.accessible
 class Result {
     private val value = "OK"
 
-    fun ref(): KProperty1<Result, String> = ::value
+    fun ref() = Result::class.properties.single() as KProperty1<Result, String>
 }
 
 fun box(): String {

compiler/testData/codegen/boxWithStdlib/reflection/properties/privateClassVar.kt

@@ -5,7 +5,7 @@ import kotlin.reflect.jvm.accessible
 class A {
     private var value = 0
 
-    fun ref(): KMutableProperty1<A, Int> = ::value
+    fun ref() = A::class.properties.single() as KMutableProperty1<A, Int>
 }
 
 fun box(): String {

compiler/testData/codegen/boxWithStdlib/reflection/properties/protectedClassVar.kt

@@ -1,10 +1,11 @@
 import kotlin.reflect.IllegalPropertyAccessException
 import kotlin.reflect.jvm.accessible
+import kotlin.reflect.KMutableProperty1
 
 class A(param: String) {
     protected var v: String = param
 
-    fun ref() = ::v
+    fun ref() = A::class.properties.single() as KMutableProperty1<A, String>
 }
 
 fun box(): String {