Add the running of Plugin Check back to our helper files

[dkotter]

Description of the Change

Coming out of #1023, we removed the scanning of our helper files from Plugin Check as it wanted us to add a code snippet to prevent direct file access but this caused issues with PHPCS. After doing some more digging, found that when PHPCS is run, it will load your composer autoload file and this in turn will load any files you are directly loading via composer (as opposed to loading via psr-4). We do this for our helper files and so when you add an exit statement to these files, this stops PHPCS from running.

There are a few fixes for this but seemed the easiest was to change from using exit to using return so that's what I've done in this PR. In addition, noticed a few PHPCS warnings around the use of heredoc instead of nowdoc so fixed those up as well.

How to test the Change

Nothing really needed other than ensuring Plugin Check passes and PHPCS also passes

Note

E2E tests aren't working on WP trunk, assuming due to upstream issues

Changelog Entry

Fixed - Ensure our helper files don't allow direct file access

Credits

Props @dkotter

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• All new and existing tests pass.