FileWrapper API is WebRTC private, so exposing absl::string_view overload for thrid-party users. Bug: b/301228802 Change-Id: Id81775c8078e61eafe9bee53a4cba6ac476b11d6 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/321460 Commit-Queue: Artem Titov <titovartem@webrtc.org> Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org> Cr-Commit-Position: refs/heads/main@{#40798}