[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/FreeFunctionCalledAsExtension.fir.kt

@@ -0,0 +1,13 @@
+fun foo(a: (String) -> Unit) {
+    "".<!UNRESOLVED_REFERENCE!>a<!>()
+}
+
+
+
+interface A : (String) -> Unit {}
+
+fun foo(a: @ExtensionFunctionType A) {
+    // @Extension annotation on an unrelated type shouldn't have any effect on this diagnostic.
+    // Only kotlin.Function{n} type annotated with @Extension should
+    "".<!UNRESOLVED_REFERENCE!>a<!>()
+}