Export all react-native methods needed to replace rect-native-notifications

Summary: This differential implements all RCT_EXPORTED methods needed to replace react-native-notifications. Methods are implemented as in Ashoats fork.

Test Plan: This will be a matter of subsequent diffs, but for the sake of testing one can replace NotificationsIOS.<...> methods with CommIOSNotifications methods of the same name.

Reviewers: tomek, atul, ashoat

Reviewed By: ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D6072