Move callable reference diagnostic tests to non-stdlib

compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsExtension.kt

@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KMemberFunction0
+
+class A {
+    fun foo() = 42
+}
+
+fun A.foo() {}
+
+fun main() {
+    val x = A::foo
+
+    checkSubtype<KMemberFunction0<A, Int>>(x)
+}