Coding standards for sector_workflow from drupal-check

PHPStan shows a few code problems that we need to fix so that it can be enabled as part our our build pipeline running green.

  Line   sector/modules/sector_workflow/sector_workflow.module                                                   
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  50     Call to an undefined method Drupal\Core\Cache\RefinableCacheableDependencyInterface::setCacheMaxAge().  
  83     Call to an undefined method Drupal\Core\Entity\RevisionableInterface::get().                            
  94     Call to an undefined method Drupal\Core\Entity\RevisionableInterface::get().                            
  107    Call to an undefined method Drupal\Core\Entity\RevisionableInterface::get().                            
  115    Call to an undefined method Drupal\Core\Entity\RevisionableInterface::get().                            
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  Line   sector/modules/sector_workflow/src/Plugin/Block/ContentModerationBlock.php                      
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  88     Method Drupal\Core\Form\FormBuilderInterface::getForm() invoked with 2 parameters, 1 required.  
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A few can be fixed by adding @var comments and doing a bit of code cleanup. The getForm one needs to be ignored since Drupal allows unlimited magic arguments.