[FrameworkBundle] Add shortcut methods to controllers

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11166
| License       | MIT
| Doc PR        | 

To-do list : 
- [x] submit changes to the documentation

Added redirectToRoute, addFlash, isGranted and checkGranted to controllers. The code seems so simple I didn't feel like adding controller tests was needed since we're just shortcuting other services calls.
Maybe we should add an interface for flashbags and make Session implement it then check if it does in this method.