Move callable reference diagnostic tests to non-stdlib

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

@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// FILE: a.kt
+
+package first
+
+class A
+
+fun A.foo() {}
+fun A.bar() {}
+fun A.baz() {}
+
+// FILE: b.kt
+
+package other
+
+import kotlin.reflect.KExtensionFunction0
+
+import first.A
+import first.foo
+
+fun main() {
+    val x = first.A::foo
+    first.A::<!UNRESOLVED_REFERENCE!>bar<!>
+    A::<!UNRESOLVED_REFERENCE!>baz<!>
+
+    checkSubtype<KExtensionFunction0<A, Unit>>(x)
+}