Strict types support

[millnut]

With Drupal core moving towards strict types, more info I've added a test pipeline in preparation localgovdrupal/localgov_project#153 which has highlighted some failures which we should fix.

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  Line   modules/contrib/localgov_guides/localgov_guides.module        
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  180    Call to function in_array() requires parameter #3 to be set.  
  181    Call to function in_array() requires parameter #3 to be set.  
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  Line   modules/contrib/localgov_guides/src/ChildParentRelationship.php   
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  64     Call to function array_keys() requires parameter #3 to be set.    
  87     Call to function array_keys() requires parameter #3 to be set.    
  96     Call to function array_search() requires parameter #3 to be set.  
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  Line   modules/contrib/localgov_guides/tests/src/Kernel/OverviewPageIntegrity.php  
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  55     Call to method Drupal\KernelTests\KernelTestBase::setUp() with              
         incorrect case: setup                                                       
  100    Call to function array_search() requires parameter #3 to be set.            
  101    Call to function array_search() requires parameter #3 to be set.            
  120    Call to function array_search() requires parameter #3 to be set.            
  121    Call to function array_search() requires parameter #3 to be set.            
  122    Call to function array_search() requires parameter #3 to be set.            
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