Report error when free function is called as extension

compiler/testData/diagnostics/tests/FreeFunctionCalledAsExtension.kt

@@ -0,0 +1,3 @@
+fun foo(a: (String) -> Unit) {
+    "".<!FREE_FUNCTION_CALLED_AS_EXTENSION!>a<!>()
+}

compiler/testData/diagnostics/tests/FreeFunctionCalledAsExtension.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun foo(/*0*/ a: (kotlin.String) -> kotlin.Unit): kotlin.Unit

compiler/testData/diagnostics/tests/resolve/invoke/errors/receiverPresenceErrorForInvoke.kt

@@ -5,7 +5,7 @@ fun test1(f: String.() -> Unit) {
 }
 
 fun test2(f: (Int) -> Int) {
-    1.f(<!TOO_MANY_ARGUMENTS!>2<!>)
+    1.<!FREE_FUNCTION_CALLED_AS_EXTENSION!>f<!>(<!TOO_MANY_ARGUMENTS!>2<!>)
 
-    2.(f)(<!TOO_MANY_ARGUMENTS!>2<!>)
+    2.<!FREE_FUNCTION_CALLED_AS_EXTENSION!>(f)<!>(<!TOO_MANY_ARGUMENTS!>2<!>)
 }