Append newline to EOF for .txt test data files

Reverts and fixes 102f0d3

compiler/testData/resolvedCalls/invoke/bothReceivers.txt

@@ -13,4 +13,4 @@ Resulting descriptor: fun Int.invoke(): Unit defined in Foo
 
 Explicit receiver kind = BOTH_RECEIVERS
 Dispatch receiver = f {Foo}
-Extension receiver = 1 {Int}
+Extension receiver = 1 {Int}