chore: add phpstan to CI

[usu]

• Adds phpstan to CI (didn't test it - hope it goes through 😄). Yaml is copied from FOSHttpCache
• Fixes all level-1 errors, except one remaining error which will be fixed by Remove deprecated code #618
• After that, we can fix and increase higher levels by separate PRs

[usu]

The new workflow "static" triggers quite a lot of errors "unknown class", which is due to references to dependencies which are dev-dependencies.
I could easily fix this by adding a REQUIRE_DEV: "true" to the phpstan-src job. But I wonder if this is correct, or whether all these dependencies should actually be non-dev dependencies...

[dbu]

thanks for looking into this.

dang. good old "optional dependencies" saying hello :-|

i am not sure how optional they really are, a couple places looks to me like it would simply error if thats not available. lets move console and security core & http to the requirements. i would assume most symfony applications use those anyways. and require twig like you require jean-beru - twig really is an optional integration.

[usu]

Fixed as suggested & ready to merge.

Actually console is optional, the services are only loaded when Symfony\Component\Console\Application is available:
https://github.com/FriendsOfSymfony/FOSHttpCacheBundle/blob/2.x/src/DependencyInjection/FOSHttpCacheExtension.php#L105
https://github.com/FriendsOfSymfony/FOSHttpCacheBundle/blob/2.x/src/DependencyInjection/FOSHttpCacheExtension.php#L541

However, twig is currently not treated optional. I will fix this in a separate PR.

[dbu]

the remaining failure is for ContextInvalidationLogoutHandler which was symfony 5 only and is being deleted in #618

i merge this as-is with the phpstan failure. thanks for the help!