Summary:
While it would be better to be able to do all of the ownership metadata at the Buck macro level, that proved to be more work than expected.
This diff adds the corresponding pfh label to all targets in `xplat/js/react-native-github` that have a Supermodule label. Once the migration is complete the Supermodules labels will be able to be removed.
Reviewed By: cortinico
Differential Revision: D35221544
fbshipit-source-id: d87d5e266dfb5e6ee087251dc34dff5db299bbaf
ceae48c0f7