feat: use action scheduler when available

[HardeepAsrani]

Summary

This PR creates wrapper functions for WP_Cron in order to use Action Scheduler when available.

Note: This PR is made against #1028 to cover latest cron uses added by the PR, and must be merged against the PR or to development after the initial PR is merged.

Will affect visual aspect of the product

No

Screenshots

Test instructions

• Cron should work as before.
• To test with Action Scheduler, you can install WooCommerce and then use the plugin.

Check before Pull Request is ready:

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

Closes #https://github.com/Codeinwp/feedzy-rss-feeds-pro/issues/785.

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🎉 This PR is included in version 5.0.0 🎉

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