Fix services configuration, remove code for old SF kernels.

[dsoriano]

This PR update the lexik_translation.translator service definition that fix the cache reset issue mentionned in #487

All code depending on old Symfony kernels versions has been removed too.

[bartmcleod]

@dsoriano I'm afraid newer PR's have been merged before this one and now there are conflicts. I hope you can find the time to resolve them.

[dsoriano]

@bartmcleod I fixed the conflicts. There was a lot of changes in the last commits (good job to them ! 👍), and I don't had time to explore and understand all the changes, but I found some coding errors in the new decorator. I'm not sure if it's actually used but for sure there will be errors. In example the contructor override some values of $this->configs wich is marked as readonly.

I actually don't understand why to add a decoraor. This is the Translator class to be moved to a decorator because now Symfony original Translator is taggued as @final and we should not extend it.

If I can I will try to understand the changes and submit fixes.

BTW the tests are ok 😉