[SecurityComponent] Added a "target_forward" option

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | None
| License       | MIT
| Doc PR        | symfony/symfony-docs#3364

This PR add an `target_forward` option that makes the `DefaultAuthenticationSuccessHandler` to forward instead of redirect if login is successful.

A use case is using `XmlHttpRequest`s, `302 Found` redirects might not works with CORS.