Add Google Drive scopes

Summary:
Add Google Drive privileges to the google provider.
While at it, remove unused services from the provider description.
This is the first step to integrate kio-gdrive with kaccounts.

Test Plan: The new scopes are correctly retrieved by a `GetCredentialsJob`.

Reviewers: mck182, apol

Differential Revision: https://phabricator.kde.org/D4638