[Translation] added method to expose collected message

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | #2435 
| License       | MIT
| Doc PR        | symfony/symfony-docs#3386
@WouterJ It's perfectly right to get every domain if you pass an empty list. The argument filters the required domains (see phpdoc), i.e. an empty filter will return everything. Pretty logical.
Btw, it's the same as in `Route::setScheme`.