Implement local server to handle OAuth callbacks for Spotify CLI

[drn]

See how official Github CLI handles this:

http://127.0.0.1:62792/callback?browser_session_id=9725a29bd99eff9822916673b39775c7d4c4bead&code=114d1a7ebd29b36afc93&state=6e24da083862f90a58b1

https://github.com/cli/cli/blob/d9083200504ddbe8ffe590ef227890423b6668ee/auth/oauth.go#L40