Add refresh option to client.getAccessToken + middleware

[flash42]

Goals

1. Be able to force refresh the access token from the client via calling client.getAccessToken

Non-Goals

Background

The Auth0Client.getAccessToken has the refresh option already: auth0/nextjs-auth0#2055.
The client version - can be called in client context - of the getAccessToken doesn't support the refresh parameter yet, nor does the SDK route for access-token has a refresh parameter.

With this silent refreshing can be done from the client context, for example when the application decides that the permissions should be refreshed.

Proposal

The client side getAccessToken should have similar API to the Auth0Client.getAccessToken - having an optional refresh parameter. Also the access-token SDK route should handle the optional refresh parameter.

I'm interested in implementing this.