[LiveComponent] Add setRouteLocale in TestLiveComponent

[smnandre]

Q	A
Bug fix?	no
New feature?	yes
Issues	Fix #1565
License	MIT

The live_component route can be localized. It then requires the {_locale} the parameter to be defined.

# config/routes/ux_live_component.yaml
  live_component:
      resource: '@LiveComponentBundle/config/routes.php'
-     prefix: /_components
+     prefix: /{_locale}/_components

This PR adds a setRouteLocale method in TestLiveComponent to help in this situation.

$testComponent = $this->createLiveComponent('Acme:Foo');
$testComponent->setRouteLocale('de');

// $testComponent is rendered with the 'de' locale

Thank you @javiereguiluz for the idea and your help :)

[javiereguiluz]

Thanks!

[javiereguiluz]

Thank you Simon.