Request a refresh token from Google

[m-mohr]

The Google OIDC implementation is not really standards-compliant. It's not an EE specific issue. I'm not sure where the right place would be to report this to Google, but it's documented on the web in various threads, some examples:

• https://developers.google.com/identity/openid-connect/openid-connect (look for access_type)
• https://community.auth0.com/t/google-authorization-offline-access/7355
• https://stackoverflow.com/questions/65910981/how-to-request-offline-access-from-google-using-addopenidconnect-in-asp-net-c

In OIDC an offline_access scope is usually supported, but Google added a proprietary access_type parameter instead.

openEO follows the OIDC specification and Google deriving slightly from it just makes it not work nicely together.
I don't want to hardcode specific behaviour into generic openEO libraries just for Google.

Something we could think about is Open-EO/openeo-api#534