[HttpFoundation] Added the 7xx HTTP Status Codes to the HttpFoundation/Response object.

Added the 7xx HTTP Status codes defined [here](https://github.com/joho/7XX-rfc) in order to make use of them in the Response object.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | /symfony-docs/blob/master/components/http_foundation/introduction.rst#response
This is wrong, the 6xx range is still invalid. :-1: