Revert "[cpp] Copy-paste react-native internal Promise utils into separate file"

Summary:
This reverts commit 26c185c7116bc80cfd3292ef46a73e745f0c6513.

We don't need it anymore because I found a way to compile Folly on Android.

Test Plan: Tested in combination with following diffs

Reviewers: karol-bisztyga, palys-swm

Reviewed By: palys-swm

Subscribers: KatPo, Adrian, atul

Differential Revision: https://phabricator.ashoat.com/D1132