Refactor permissions table to have foreign key to clients table with cascade delete

[mikelax]

Feature Overview

Is your feature request related to a problem? Please describe. In this comment it was discussed that the column permissions.clientkey is not actually a foreign key to the clients table.

Describe the solution you'd like This column should be updated to be a true foreign key with the on delete cascade clause to match other clientkey foreign keys.

Additional context

Add any other context or screenshots about the feature request here.