upkeep/163: Fix fatal error on PHP 5.6

[Sidsector9]

Description of the Change

This PR does the following:

1. Moves the class Simple_Page_Ordering to a separate file.
2. Require class-simple-page-ordering.php only when platform validation passes.

Closes #163

How to test the Change

Please follow steps from the issue.

Changelog Entry

Fixed - Fatal errors on PHP 5.6

Credits

Props @peterwilsoncc @Sidsector9

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[iamdharmesh]

@Sidsector9 Thank you for the PR.

PR adds composer dependency to the plugin but it seems we have ignored the vendor folder in .distignore file. It may result in vendor folder missing in the release zip. Could you please help to check it once?

Also, we have to add steps for composer package installation in our GH action workflows. especially in deploy workflow. Could you please help with it?

Thank you.

[peterwilsoncc]

In the event further composer dependencies are added at a later date includingthis here may cause problems if the new dependencies require > PHP 5.6

Would it be possible to do one of the following:

• only require the compatibility checker in the vendor path
• install the compatibility checker outside of vendor and require it from the custom location

[Sidsector9]

@peterwilsoncc I've taken the approach to move the library from vendor to 10up-lib directory and also loaded the SPO main class after the validation is completed.

[iamdharmesh]

Thanks for the PR @Sidsector9. Code LGTM! and it tests well (Didn't throw any fatal error on 5.6 now).

In release build zip I have noticed some .md files in 10up-lib folder but it doesn't seems a blocker here. So, we are good to go here.

Thank you.

[Sidsector9]

Thanks for testing @iamdharmesh
The files you're seeing is expected as you can also see them in the vendors directory.
I'll resolve this in the next release of WP Compat Validator Tool.