Various small bug fixes

Context

Summary

This PR can be summarized in the following changelog entry:

Range of small bug fixes

Relevant technical choices:

Column::register_hooks(): bug fix

The Column::quick_edit_remove_original() method only expects one parameter, so no need to ask WP for 2.

Newsletter::newsletter_signup_form(): bug fix

The wp_nonce_field() function by default displays the field.

This means that, as things were, the nonce field would be echo'd out when the function was called + would add a 1 to the $html string being created. The resulting $html string would not contain the nonce field and the nonce field would not be between the <form> tags.

Fixed by setting the $display parameter to false.

Ref: https://developer.wordpress.org/reference/functions/wp_nonce_field/

QA: remove redundant code

The explode() function will always return an array, so strict comparing the return value with an empty string will never result in a passing condition.

Ref: https://www.php.net/manual/en/function.explode.php

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

Check that the newsletter form still works as expected
In the plugin settings, Display tab, section Show original item, enable In a column in the Post list and save
clone a post in the post list
quick edit the copy and check that you can see Delete reference to original item. The original item this was copied from is: <title of the original post>

Relevant test scenarios

[ ] Changes should be tested with the browser console open
[ ] Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
[ ] Changes should be tested on different editors (Block/Classic/Elementor/other)
[ ] Changes should be tested on different browsers
[ ] Changes should be tested on multisite

Test instructions for QA when the code is in the RC

[x] QA should use the same steps as above.

QA can test this PR by following these steps:

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

UI changes

[ ] This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Documentation

[ ] I have written documentation for this change.

Quality assurance

[x] I have tested this code to the best of my abilities
[ ] I have added unittests to verify the code works as intended

Innovation

[x] No innovation project is applicable for this PR.
[ ] This PR falls under an innovation project. I have attached the innovation label and noted the work hours.

Fixes #

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/ui/newsletter.php	0	1	0.0%
<!--	Total:	1	2	50.0%	-->

Totals
Change from base Build 6985565176:	0.04%
Covered Lines:	1236
Relevant Lines:	2462

Yoast / duplicate-post