Support PHP Code Sniffer

[josephdpurcell]

Add the ability to run the drupal-check with a flag that checks for PHP Code Style using the drupal/coder project.

[josephdpurcell]

Unassigning myself.

After looking into this, it looks like all files will have to be parsed twice, once by phpstan (drupal-check's parser) and once by phpcs's parser. So, there wouldn't be any performance benefit that I know of by including phpcs in drupal-check other than the advantage of having a single CLI that includes these multiple checks.

If this is completed, take a look at https://github.com/codeclimate/codeclimate-phpcodesniffer/blob/master/Runner.php#L80. How Code Climate is triggering phpcs might give some indication of how it can be done here.

Another thing to consider: how will you tell drupal-check to run drupal coder? Is it a binary state on whether to run it, or can you also pass arguments for directories to exclude, checks to disable, etc? I didn't see an easy way to modify the config files https://github.com/mglaman/drupal-check/tree/master/phpstan such that a user of drupal-check could provide their own config or pass flags in an easy way.

[mglaman]

Reducing the scope of this project. Won't do.