[OAuth] Allow apps to generate claims for their own scopes

Currently, all claim data is generated in the validator.

We need to allow apps to fill in data for their own scopes.

added type::feature label

assigned to @nik

created merge request !799 (merged) to address this issue

mentioned in merge request !799 (merged)

closed with merge request !799 (merged)

mentioned in commit 40cb62a9