Add Notifications for New Events

[alexgraffeocohen]

This PR adds the ability for the Events Map to display notifications when new events are fetched that the Events Map doesn't already have. If there is only one new event, it will tailor the notification to the details of that event.

Also fixes a bug: we accidentally broke the "zoom into the event you just created" feature.

Some limitations of this feature:

• ~If the EventsMap is unmounted (i.e. the app is restarted in some way or somehow doesn't have enough memory to retain that screen) then we no longer know what events we previously had, so all fetched events are new again. We will ultimately rectify this with an AsyncStorage solution, but didn't want to go too far down that rabbit hole because the correct solution involves Redux. Could go there if needed, though. I think we should use Redux Persist, which will allow us to store parts of our Redux state in AsyncStorage. This would be advantageous for other reasons, such as better offline support for this app so that users, even if they lose internet connection after the app is restarted, could still see the alerts they had already fetched.~
• We display a notification if the user themselves added a new event. To prevent that unneeded notification, we need to check for the currently signed in user and then see if the new event was created by them. For that matter, we could filter our all new events created by them, since they presumably know about them. This would be a pretty easy feature to add to this PR right now.
• ~Tapping the notifications does nothing. Navigating you to the map (if there are multiple new events) or the event show screen (if there is one new event) is a bit involved, but not impossible. Just didn't have time right now, and wanted a PR out the door.~

ToDo

• [x] Store redux state in AsyncStorage
• [x] Navigate to the correct screens when tapping notifications
• [x] Present a modal explaining why we want notification permission before asking for it
• [ ] Optional: don't display notifications for events created by the current user
• [ ] Optional: don't display the snackbar if there are new events (we don't want snackbar and notification at the same time)

[arghgr]

Ok, let me know once you're done pulling the Firebase creds out and we should be good to merge! Also, another thing we might want to keep thinking about is, since you've added redux-persist (thanks for figuring that out!), is there any data in the Redux store that we don't want persisted on a user's device? I'll bring this up in the Slack.

[alexgraffeocohen]

@arghgr OK we should be all set now! I removed the plist file from the repository, cleaned up commit history so it's as if I never added it, and added the app center build script to create the plist file during the build process.

Like I said in Slack, all the info in that file is public, so I'm not going to try to reset the credentials, particularly since it's a whole thing (I'd have to delete the Firebase project and re-create it).

I also removed detox, the end to end testing framework I tried, from the repo. It started messing up our App Center builds for some reason, and I want to replace it anyway.

The interesting commits to double check would be c13a0af and 7336638.

[arghgr]

Ok, I've tested this PR and local notifications while the app is open are working, so I'm going to merge. Also added a reminder to add the gitignored file to the dev docs.