Sign In - Unique Username Checking That Works

[aaronm-2112]

As of now username checking doesn't seem to be what we want. There are 4 instances of "Aakash" in the database! lol

[JetSetDoritos]

Perhaps modify the signin flow to add accepted usernames to a list in the database or firestore, when it worked the old check used an API call for each username, which is wasteful.

For an actual production product we would have to use Firebase Functions so do a server side check for taken usernames to prevent it from being exploited, but for our purposes a local check is okay.

[aaronm-2112]

Yea I was digging around and saw a lot of that. I also saw a lot of examples where they edit firestore database rules to ensure username uniqueness that work in tandem with a "usernames" collection. I'll dig into that more later. Right now I'll just try to adjust the query to make it work.