Feature: Add WordPressLibraries to manage WP_Background_Process

[JoshuaHungDinh]

Description

This pull request introduces organizational changes and a new directory to handle the deprecated WP_Background_Process and WP_Async_Request classes more efficiently. Additionally, this addresses potential conflicts with other plugins using the same classes, specifically a fatal error experienced with the 3rd party plugin "RankMath" and our Give-Zapier plugin.

The primary motivation behind these changes is to eliminate conflicts arising from the loading of the deprecated classes without considering the plugin's scope. By creating a new namespace directory to manager the WP Background Process we can make it easier to manage any future conflicts with third party plugins.

The new namespaced classes can be found with the Framework directory, under WordPressLibraries.

Reference: https://github.com/impress-org/give-zapier/pull/63

Testing Instructions

Please see referenced PR.

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

[jonwaldstein]

👍 ready for QA