OAuth scopes for Custom Objects

Added new OAuth scopes for Custom Objects. This way you no longer need to grant scopes for Products on API clients if the clients should have access to this endpoint only.

• [API] Added scope manage_key_value_documents:{projectKey} which grants access to all the APIs for creating, modifying, deleting and viewing Custom Objects.
• [API] Added scope view_key_value_documents:{projectKey} which grants access to the APIs for viewing Custom Objects.