Using Twig CS fixer

[alexmerlin]

This feature is mostly forgotten since it was implemented. We should promote this internally so that our developers start using it on a daily basis.

Before each commit, we should validate Twig files (inside the src directory - @bidi47 correct me if I'm wrong on this one) using this command:

composer twig-cs-check

which will output any coding style error that needs to be fixed.

Then we can fix them manually or using this command

composer twig-cs-fix

Both Composer commands are defined in composer.json.

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We should also investigate if this feature can be turned into a CI tool that runs on each push - that way even if we forget to run it locally, invalid code will not get through to the default branch.