Added routes to Permissions module as well as dozens of other fixes.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | ---
| Fixed tickets | ---
| Refs tickets  | #1788
| License       | MIT
| Doc PR        | ---

Here we have no `@Route("/admin")` on the Controller, that's why we need to use @Route("/") here. If we have `@Route("/admin")` on the Controller, the slash is not needed. That's at least how I think it works :smirk: