feat: Refactor console commands to new AsCommand syntax

[robin-homberg]

Refs: DVELOPS6-169

[robin-homberg]

Fix for:

[deprecation] User Deprecated: Since symfony/console 6.1: Relying on the static property "$defaultName" for setting a command name is deprecated. Add the "Symfony\Component\Console\Attribute\AsCommand" attribute to the "Flagbit\Shopware\ShopwareMaintenance\Command\PluginSynchronizeCommand" class instead.
[deprecation] User Deprecated: Since symfony/console 6.1: Relying on the static property "$defaultName" for setting a command name is deprecated. Add the "Symfony\Component\Console\Attribute\AsCommand" attribute to the "Flagbit\Shopware\ShopwareMaintenance\Command\ConfigSynchronizeCommand" class instead.

since composer.json already requires symfony/console ^6.3 here. This shouldn't be a breaking change