Fix PHP 8.1 deprecations caused by views code

Problem/Motivation

Views passes NULLs from database queries into functions that on PHP 8.1 will trigger a deprecation.

Steps to reproduce

Run the following tests on PHP 8.1:

• core/modules/views/src/Plugin/views/HandlerBase.php run \Drupal\Tests\dblog\Functional\DbLogViewsTest
• core/modules/views/src/Plugin/views/display/PathPluginBase.php run \Drupal\Tests\rest\Unit\CollectRoutesTest
• core/modules/views/src/Plugin/views/field/Broken.php run \Drupal\Tests\views\Functional\Handler\FieldGroupRowsWebTest
• core/modules/views/src/Plugin/views/field/NumericField.php run \Drupal\Tests\comment\Functional\Views\NodeCommentsTest
• core/modules/views/tests/src/Kernel/QueryGroupByTest.php run core/modules/views/tests/src/Kernel/QueryGroupByTest.php

Proposed resolution

Fix the deprecations.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet