Add unlisted post status and filter to admin post list.

[matthewmcvickar]

Description

• Adds ' — Unlisted' next to unlisted posts in the post list, like you'd see next to a draft or private post.
• Adds 'Unlisted' as a filter above the list of posts, similar to 'Mine' or 'Drafts,' et cetera.

Screenshots

Unlisted post status added to post list item:

Unlisted post filter:

Types of changes

• Three new functions/hooks added to class-unlist-posts-admin.php.

How has this been tested?

• Tested in a development environment with hidden posts.

Checklist:

• My code is tested COULD NOT TEST
• My code passes the PHPCS tests COULD NOT TEST
• My code follows accessibility standards
• My code has proper inline documentation
• I've included any necessary tests NO TESTS EXIST
• I've included developer documentation INLINE
• I've added proper labels to this pull request NO LABELS AVAILABLE

[matthewmcvickar]

Update: I was able to get the PHPCS to run, and it found no problems with this file:

❯ ./vendor/bin/phpcs -p class-unlist-posts-admin.php --standard=PHPCompatibilityWP
. 1 / 1 (100%)

[matthewmcvickar]

Another update: I added localization for the 'Unlisted' post status string.

[Nikschavan]

Happy to fix this up myself in a few days

[Nikschavan]

Thank you for the PR @matthewmcvickar, I will get this merged and released in a few days

[matthewmcvickar]

Excellent! Thank you!

[Nikschavan]

btw @matthewmcvickar I created a few follow-up PRs #41 and #42 to add few more changes

1. Posts filter is displayed on all public post types
2. The count of the posts is relative to that particular post type.
3. Dynamically build the link to post status relative to the current post type.