[EE] Allow unauthenticated access to Repositories Files API GET endpoints

EE version of gitlab-org/gitlab-ce!8149

enabled an automatic merge when the build for 48aa63bc succeeds

MWBS set

closed

Thanks @smcgivern! However, since !8149 uses some code added by !8148 (e.g. the shared examples for the API status code), I'm going to open a new MR that port both !8148 & !8149 (since they're related that makes sense).