Remove signInAnonymously from authenticated API routes

[tinyherocarrot]

For some reason signInAnonymously needs to be called before each authenticated API route. We should find some way to eliminate this step

Motivation

Anonymous sign in causes a bunch of anonymous users in the user list. Also a ding on performance.

Problem

The server/backend doesnt know about authentication state on the client side, probably because API routes are built before the active session is retrieved. I can pass in the 'auth' object from middleware, but 'auth' object still won't be passed along to the firebase req (ie. update)

Approaches

• Use a 'wrapper' to get the id token either from req.header or cookies, verifyIdToken with firebase admin, then make firebase request using firebase-admin (which has unfettered access). We can do an extra check before making the req to be sure the user is admin maybe something like Merging in Categories endpoints #2 down below(https://dev.to/dingran/next-js-firebase-authentication-and-middleware-for-api-routes-29m1)
• Can use Claims to create an "admin" role (https://firebase.google.com/docs/auth/admin/custom-claims#set_and_validate_custom_user_claims_via_the_admin_sdk)
• There might be something useful on this page from the Firebase docs detailing integration with Next.js (https://firebase.google.com/docs/hosting/frameworks/nextjs#optional_integrate_with_firebase_authentication)