Codegen for callable reference expressions

#KT-1183 In Progress

compiler/testData/codegen/box/callableReference/classMemberFromExtension.kt

@@ -0,0 +1,12 @@
+class A {
+    fun o() = 111
+    fun k(k: Int) = k
+}
+
+fun A.foo() = this.(::o)() + this.(A::k)(222)
+
+fun box(): String {
+    val result = A().foo()
+    if (result != 333) return "Fail $result"
+    return "OK"
+}