Dropbox auth/* endpoints.
auth/*
POST auth/token/from_oauth1.
auth/token/from_oauth1
POST auth/token/revoke — empty/null body.
auth/token/revoke
null
@type opts() :: keyword() | map()
@type result() :: {:ok, term()} | {:error, Noizu.Dropbox.Error.t()}
@spec token_from_oauth1(String.t(), String.t(), opts()) :: result()
@spec token_revoke(opts()) :: result()