Introduce contracts for refreshing and revoking tokens

[itambek-godaddy]

It looks like a few providers are implementing token refreshing and revoking support, but there is no contract/interface which they implement. This can lead to different APIs across the providers, for example:

• Apple has a refreshToken method, which returns the raw ResponseInterface
• Mollie has a getRefreshTokenResponse method, which returns the parsed body as an array

It would be great to have contracts/interfaces in the Manager repo, so that we would have consistent method names and return values across different providers.

I think these interfaces should be opt-in, so that the individual providers can choose wether to implement them or not.

[audunru]

I've been wondering about this as well.

In Socialite's AbstractProvider, there is a refreshToken method. It does a standard call to refresh a token, but it just returns the token. As far as I can see, the access token and refresh token which has been set on the user is not updated. So it seems this excercise is left to the reader.