Add missing DocBlocks and parameter descriptions for a wide variety of properties and methods in `WP_Upgrader`, `Plugin_Upgrader`, `Theme_Upgrader`, `Language_Pack_Upgrader`, `Core_Upgrader`, and `File_upload_Upgrader`.

Props jdgrimes, DrewAPicture.

See #29086.

Built from https://develop.svn.wordpress.org/trunk@30758


git-svn-id: http://core.svn.wordpress.org/trunk@30748 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Restore missing line in DocBlock for `WP_Tax_Query::get_sql_for_clause()`.

Props kpdesign.
See [30622], #30469.

Built from https://develop.svn.wordpress.org/trunk@30759


git-svn-id: http://core.svn.wordpress.org/trunk@30749 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Customizer - Widgets: add feedback for screen readers when moving up or down. Props adamsilverstein, afercia. Fixes #28892.
Built from https://develop.svn.wordpress.org/trunk@30760


git-svn-id: http://core.svn.wordpress.org/trunk@30750 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Always return a value in `Plugin_Upgrader::deactivate_plugin_before_upgrade()`. Props jdgrimes. Fixes #29088.
Built from https://develop.svn.wordpress.org/trunk@30761


git-svn-id: http://core.svn.wordpress.org/trunk@30751 1a063a9b-81f0-0310-95a4-ce76da25c4cd