[FrameworkBundle] Added configuration for additionnal request formats

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | https://github.com/symfony/symfony/issues/8934
| License       | MIT
| Doc PR        |  ~ 

# TODO
  - [x] Fix wrong xml configuration definition (Thanks @WouterJ)
  - [ ] Write documentation (new entry or replace symfony.com/doc/current/cookbook/request/mime_type.html ?)