GitLab

1. Port https://codereview.chromium.org/2115653002/
   to crnet_environment.mm
2. Port https://codereview.chromium.org/2110803002/ to
   crnet_environment.mm and cronet_environment.cc
3. Override CrNet FrameworkBundle, so that the icudtl.dat and
   IDS_ACCEPT_LANGUAGES can be read from the framework bundle itself.
4. Use base::mac::FrameworkBundle() instead of [NSBundle mainBundle].

Review-Url: https://codereview.chromium.org/2137623002
Cr-Commit-Position: refs/heads/master@{#404535}