Use a permission to view the Subscription page

Thanks @ericpoir for your proposed change. While this usually makes sense, I wonder in this scenario, what the use case would be where you allowed for subscriptions but not to see the list of own subscriptions?

And if we move forward with this, please turn the patch into an issue fork and MR, since patches will soon not be supported any more. Also, with MRs we get the benefits of GitLab CI, which tests the code for every commit.