Refactor: remove FormatObjectList dependency and update logic locally for PHP 8 compatibility

[jonwaldstein]

Resolves GIVE-3071

Description

This removes the kjohnson/format-object-list package and replaces FormatObjectList logic locally for PHP 8 compatibility.

Fixes the following:

Deprecated: Creation of dynamic property FormatObjectList\Formatter::$data is deprecated in /home/zezamuyuya1147/web/tops-kea-b227b2.instawp.xyz/public_html/wp-content/plugins/give.4.14.0-dev-1770125818-da8933dc/vendor/kjohnson/format-object-list/src/Formatter.php on line 15

Deprecated: Creation of dynamic property FormatObjectList\Formatter::$callback is deprecated in /home/zezamuyuya1147/web/tops-kea-b227b2.instawp.xyz/public_html/wp-content/plugins/give.4.14.0-dev-1770125818-da8933dc/vendor/kjohnson/format-object-list/src/Formatter.php on line 16

Deprecated: Creation of dynamic property FormatObjectList\Formatter::$data is deprecated in /home/zezamuyuya1147/web/tops-kea-b227b2.instawp.xyz/public_html/wp-content/plugins/give.4.14.0-dev-1770125818-da8933dc/vendor/kjohnson/format-object-list/src/Formatter.php on line 15

Deprecated: Creation of dynamic property FormatObjectList\Formatter::$callback is deprecated in /home/zezamuyuya1147/web/tops-kea-b227b2.instawp.xyz/public_html/wp-content/plugins/give.4.14.0-dev-1770125818-da8933dc/vendor/kjohnson/format-object-list/src/Formatter.php on line 16

Affects

• Affects LocationList::getCountries and LocationList::getStates used in the donor dashboard and GiveWP onboarding

Visuals

N/A

Testing Instructions

ZIP: https://github.com/impress-org/givewp/actions/runs/21718755768

• Make sure the list of states and countries work properly in the donor dashboard
• Make sure the list of states and countries work properly in GiveWP onboarding

Pre-review Checklist

• Acceptance criteria satisfied and marked in related issue
• Relevant @unreleased tags included in DocBlocks
• Includes unit tests
• Reviewed by the designer (if follows a design)
• Self Review of code and UX completed

[glaubersilva]

@jonwaldstein Looks good! 👍