support PSR-11 compatible DI containers

[xabbuh]

Q	A
Bug fix?	no
New feature?	yes
Doc updated	no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets
License	Apache-2.0

To be able to use lazily-loaded event dispatchers even with private services in JMSSerializerBundle we can leverage the ServiceLocator feature introduced in Symfony 3.3. However, that class does not depend on the ContainerInterface from the DI component, but just needs an arbitrary PSR-11 compatible ContainerInterface implementation (which the Symfony containers implements too since Symfony 3.3). The same applies to the LazyHandlerRegistry.

[goetas]

HI! nice! thanks a lot for the PR!

I was reading https://symfony.com/blog/new-in-symfony-3-3-service-locators but I really did not get how it works... it looks that the ServiceLocator is just a service factory with visibility only on a specific subset of services... am I right?

[goetas]

Do you mind add psr/container in the require-dev section and add some basic test? this should be the right place?

[xabbuh]

@goetas Tests added, do I need to update the changelog file too? Oh and I also updated the branch alias as I think that this change qualifies as a new feature.

[goetas]

to me looks just great! 🕺
will check it soon and merge it!
no worries for the changelog, is automatically generated

[goetas]

thanks!