Plugins: Add hidden File column to plugin list table

[crweiner]

See Trac ticket: https://core.trac.wordpress.org/ticket/65145

Summary

Adds a hidden-by-default File column to the plugins list table so installed plugins can be identified by their plugin file/basename.

This is an alternative to #11674. That PR helped validate the Screen Options direction, but this patch takes a slightly different approach by exposing the installed plugin file ($plugin_file) in a File column rather than exposing a Slug column.

Why this approach

Using File may be a better fit for the concerns raised in the ticket because it reflects the actual installed plugin identifier that core already has reliably for all plugins, including:

• WordPress.org plugins
• premium/custom plugins
• plugins with multiple entry files in one directory
• must-use plugins
• drop-ins
• multisite and custom plugin directory setups

This also avoids labeling directory/file.php as a “slug”, which is not always technically accurate.

What changed

• Adds a hidden-by-default File column to WP_Plugins_List_Table
• Displays the value of $plugin_file
• Places the column at the end of the plugins columns / Screen Options list
• Adds a responsive fix so hidden plugin columns remain hidden on narrow/mobile views
• Adds PHPUnit coverage for the new column, default hidden state, and row output

Testing

• Browser-tested on local single-site and multisite Studio sites
• Verified Installed, Must-Use, and Drop-ins views
• Verified network and subsite plugin screens on multisite
• Confirmed the File column is hidden by default, appears when enabled, and hides again when disabled
• Ran:
  • php -l src/wp-admin/includes/class-wp-plugins-list-table.php
  • php -l tests/phpunit/tests/admin/wpPluginsListTable.php
  • npm run test:php -- tests/phpunit/tests/admin/wpPluginsListTable.php

AI assistance

AI assistance: Yes
Tool(s): OpenAI Codex
Model(s): GPT 5.4 High
Used for: implementation drafting, test drafting, and local QA assistance. Final code, testing, and validation were reviewed and completed by me.

[github-actions]

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[github-actions]

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[github-actions]

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