Introduce module 'reflection', move KFunctionN to it

Metadata for KFunction classes is now longer serialized along with built-in
classes. This effectively means that it's no longer possible to find KFunction
classes via dependency on built-ins. There should be a kotlin-runtime library
in the specified classpath for reflection types to be resolvable.

A lot of tests were moved and changed, because tests on callable references
require stdlib in classpath from now on

compiler/testData/codegen/boxWithStdlib/callableReference/function/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"
+}