Support references to extension properties in JVM codegen

#KT-1183 In Progress

compiler/testData/compileKotlinAgainstKotlin/PropertyReference.A.kt

@@ -0,0 +1,6 @@
+package a
+
+public var topLevel: Int = 42
+
+public val String.extension: Long
+    get() = length.toLong()

compiler/testData/compileKotlinAgainstKotlin/PropertyReference.B.kt

@@ -0,0 +1,14 @@
+import a.*
+
+fun main(args: Array<String>) {
+    val f = ::topLevel
+    val x1 = f.get()
+    if (x1 != 42) throw AssertionError("Fail x1: $x1")
+    f.set(239)
+    val x2 = f.get()
+    if (x2 != 239) throw AssertionError("Fail x2: $x2")
+
+    val g = String::extension
+    val y1 = g.get("abcde")
+    if (y1 != 5L) throw AssertionError("Fail y1: $y1")
+}