Add some kind of authentication/authorization

[billnapier]

I'm not super psyched to be building this myself, but I also don't really need anything complicated. I'd like it such that the membership chair can login, as can the District Executive. Since this is just two people, we can actually do something super hacky like a shared secret (stored in firebase).

Or something even better, like google login integration, and then checking the returned login against an allowlist of email addresses (or something).

Like building out pages to control who can and cannot access the app is super low on my list, this will all likely be configured via direct data writes to firestore.

[billnapier]

For now, have just deployed with IAP to control access.