Add support for patch rc versions

Summary:
We might want to publish some new versions of React Native with experimental feature to allow some partners to test whether those versions fixes some reported issues, before creating a proper stable version for the whole ecosystem.

The infra is mostly [setup for this](https://www.internalfb.com/code/fbsource/[496a64d180faab501b8598aa0ec26d47454fb961]/xplat/js/react-native-github/scripts/releases/utils/version-utils.js?lines=149), already. The only detail we need to take care of is not to move the `next` tag.

[Internal]

Reviewed By: cortinico, huntie

Differential Revision: D56578456

fbshipit-source-id: 8dcc674aab5f85077c1b3e6580c5aeb99226eff8