B7.4 OAuth2 Token Endpoint

[joshgarde]

Create an endpoint which accepts the code query parameter from the OAuth2 flow and utilizes it to retrieve an access_token from the OAuth2 provider. This is the endpoint which is provided to the OAuth2 flow as redirect_uri and which the OAuth2 provider will redirect to once they authenticate the user. This endpoint should also handle user creation in the database, if the user is not already created and generating a session. It should also redirect the user, once the code is verified and exchanged for an access_token, to the application's homepage.

Eg. http://LETSMESH/authorize/discord/token?code=abcdefg