Add refreshTokenWithClientId option, to send client_id when using a refresh token

[rob-a-bolton]

Some OAuth providers (e.g. Keycloak) require that client_id is sent when using a refresh token.
This patch adds the refreshTokenWithClientId option that may be used similarly to the refreshTokenWithCredentials.
When true, the request body for the token refresh will also send a client_id parameter fetched from the state.
I have locally tested this patch and it produces the desired behaviour, though I've not commit the packed dist bundle files yet.

The refreshTokenWithCredentials option wouldn't be suitable when using a public client as no credentials are known.

Evidence of Keycloak's behaviour may be found on the discourse.

[the-kenny]

We're having the same problem in our setup. It would be great if this option could be merged so that we can stop using a forked version of fhir.js.