Append newline to EOF for .txt test data files

Reverts and fixes 102f0d3

compiler/testData/resolvedCalls/invoke/extensionReceiverAsReceiverForInvoke.txt

@@ -12,4 +12,4 @@ Resulting descriptor: fun Foo.invoke(): Unit defined in root package
 
 Explicit receiver kind = EXTENSION_RECEIVER
 Dispatch receiver = NO_RECEIVER
-Extension receiver = f {Foo}
+Extension receiver = f {Foo}