Force autoconfigure for schema services

[leoloso]

Before, if $skipSchema is true, then schema services would not be registered in the container.

That created a problem: the ModuleResolver needs to show the name for those services in the Modules page, but since a disabled module was not registered in the container, we couldn't access its name.

This PR changes the procedure:

• Schema services are always registered in the container
• But, if $skipSchema is true, they are just not initialized

Schema services are all of the AttachExtension type. Hence, "not initialized" means that they do not execute their attach method.

To do this, we created a new ForceAutoconfigureYamlFileLoader class which will always set the default autoconfigure option in the container, with value !$skipSchema.

And then, in the CompilerPass to register all AttachExtension objects in the registry, we only register those objects with autoconfigure => true (i.e. $skipSchema => false)