generate:cest: Adding `declare(strict_types=1);` and return type `void` to generated files

[TavoNiievez]

In the past I was against adding : void at the end of methods because it doesn't add anything relevant to the tests and because it can make the suite tests harder to read. Strict types were also suggested by me, but it was also not decided to add them. I even suggested that Cest should be 'final' classes, but again, the simpler the default generated code the better I guess was the reasoning.

[ThomasLandauer]

Well, you can certainly see it as noise. But that's the way that PHP has been taking over the last view years.

• void: psalm is reporting:

  MissingReturnType: Method App\Tests\Acceptance\FirstCest::_before does not have a return type, expecting void

• declare(strict_types=1); is good practice today
• And now I even added final - overlooked that yesterday :-)
• Thinking some more about it, I now even added $scenario (see https://codeception.com/docs/AdvancedUsage) - probably rarely used, but very hard to find in the docs...

My main argument is: That's the way good PHP code should look nowadays, so we should gently guide people to this direction. And the generated files are just a suggestion - anybody can easily delete the stuff they don't want.