Setup Signin API

[timjacksonm]

• [x] Create Signin API Endpoint
• [x] Possibly use CredentailsProvider with nextauth?? Would be added to [...nextauth].js
• [x] Might have to update the signin callback. Not sure if this provider uses that.
• [x] Setup emailVerified logic that denies a user login that isn't verified, set it to disabled until #47 is done

https://next-auth.js.org/configuration/providers/credentials