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

compiler/testData/diagnostics/tests/functionAsExpression/DifficultInferenceForParameter.fir.kt

@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+fun <T> foo(f : (T) -> T) : T = throw Exception()
+
+fun test() {
+    val a : Int = foo(fun (x) = x)
+}