fix: handle null ini values in phpini check

[Will-thom]

Refs #9968.

Summary

• Normalize null values returned by ini_get_all() before rendering phpini:check output.
• Prevent CLI color/table rendering from receiving null for directives such as request_order or error_reporting on newer PHP runtimes.

Tests

• vendor/bin/phpunit --no-coverage tests/system/Commands/Utilities/PhpIniCheckTest.php
• vendor/bin/phpunit --no-coverage --order-by=random --random-order-seed=12345 tests/system/Commands
• utils/vendor/bin/php-cs-fixer check --ansi --verbose --diff system/Security/CheckPhpIni.php

[mergeable]

Hi there, Will-thom! 👋

Thank you for sending this PR!

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Sincerely, the mergeable bot 🤖

[michalsn]

@Will-thom Thank you for the PR. We require commits to be signed, please see this: https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/workflow.md#gpg-signing-old-commits

Please also rebase to the latest develop.