Add support for FQCN service name

[hason]

Current warning: Service Naming Conventions: Use lowercase letters for service and parameters names

Example:

services:
    Vendor\Namespace\Class:
        class: Vendor\Namespace\Class
        autowire: true

Fixes:

• [DependencyInjection] Optional class for class named services symfony/symfony#20264
• https://github.com/dunglas/DunglasActionBundle#usage

[Haehnchen]

as inside core now also supported and released by #847