add privacy manifest to RCT-Folly

[philIip]

Summary: Changelog: [Internal]

add this to the framework's resource bundle

from the audit there were callsites to fstat variants in our forked copy of boost, so use C617.1. callsites:

• RCT-Folly/folly/FileUtil.h
• RCT-Folly/folly/portability/SysStat.h

current problem with this method is that the required reasons are not currently be aggregated during app store review, so those need to live in the app's. but go ahead and add it here for now, i think apple will try to fix it.

Reviewed By: cipolleschi

Differential Revision: D55625114

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D55625114