Append terminating newline to output

[michaelnisi]

Xcode expects newline terminated files as noted in apollographql/apollo-ios#531. I found this related PR #525, so maybe a more generic solution should be considered.

This is my first contribution to this project, let alone my first lines of TypeScript, but I hope its intention comes across.

[designatednerd]

@michaelnisi mind updating this to fix the merge conflicts? I'm not entirely clear on why some builds failed, but let's see if they do again 😆

[michaelnisi]

Rebased. Failing checks seem unrelated.

[michaelnisi]

@designatednerd Skimming through the test logs… When was the last time those tests passed? 😟

[designatednerd]

I...don't know. I'll ping the tools team when they're up in 🇺🇸

[trevor-scheer]

@designatednerd tests are notoriously flaky on this repo, often resolved by the first re-run 😕, the current azure node 10 test that's failing is new to me, but I can't reproduce locally and it's not happening in the other environments. Sad to say it, but let's disregard that failure for now.

[designatednerd]

Swift stuff is good, would appreciate someone who knows typescript taking a 2nd look!