Move callable reference diagnostic tests to non-stdlib

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

@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION,-UNUSED_VARIABLE
+fun foo(x: Int, <!UNUSED_PARAMETER!>y<!>: Any) = x
+fun foo(<!UNUSED_PARAMETER!>x<!>: Any, y: Int) = y
+
+fun main() {
+    ::<!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>
+    
+    val fooRef: (Int, Any) -> Unit = ::<!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>
+}