Move callable reference diagnostic tests to non-stdlib

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

@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class B
+
+class A {
+    fun B.main() {
+        val x = ::foo
+        val y = ::bar
+        val z = ::baz
+
+        checkSubtype<KExtensionFunction0<A, Unit>>(x)
+        checkSubtype<KExtensionFunction1<A, Int, Unit>>(y)
+        checkSubtype<KExtensionFunction0<A, String>>(z)
+    }
+}
+
+fun A.foo() {}
+fun A.bar(<!UNUSED_PARAMETER!>x<!>: Int) {}
+fun A.baz() = "OK"