Fix remaining strict types errors

[millnut]

With Drupal core moving towards strict types, more info we should fix the remaining errors suppressed in the phpstan baseline.

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  Line   modules/contrib/localgov_menu_link_group/localgov_menu_link_group.module
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  91     Parameter #2 $callback of function array_walk expects callable(Drupal\Core\Entity\EntityInterface, int|string): mixed, array{Drupal\localgov_menu_link_group\MenuLinkGrouper, 'groupChildMenuLinks'} given.
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  Line   modules/contrib/localgov_menu_link_group/src/Controller/LocalGovMenuLinkGroupListBuilder.php
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  51     Parameter #1 $group of method Drupal\localgov_menu_link_group\Controller\LocalGovMenuLinkGroupListBuilder::determineParentMenuLinkLabel() expects Drupal\localgov_menu_link_group\Entity\LocalGovMenuLinkGroupInterface,
         Drupal\Core\Entity\EntityInterface given.
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  Line   modules/contrib/localgov_menu_link_group/src/Form/LocalGovMenuLinkGroupForm.php
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  80     Dynamic call to static method Drupal\localgov_menu_link_group\Form\LocalGovMenuLinkGroupForm::prepareMenuLinkOption().
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  Line   modules/contrib/localgov_menu_link_group/tests/src/Kernel/GroupAccessTest.php
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  64     Class DOMXPath referenced with incorrect case: DomXPath.
  79     Class DOMXPath referenced with incorrect case: DomXPath.
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  Line   modules/contrib/localgov_menu_link_group/tests/src/Kernel/GroupConfigImportTest.php
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  45     Call to function in_array() requires parameter #3 to be set.
  72     Call to function in_array() requires parameter #3 to be set.
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