Plugins: Show "Activate" after updating an inactive plugin from Add Plugins

[wprashed]

Trac Ticket

https://core.trac.wordpress.org/ticket/65909

Description

When updating an inactive plugin from the Add Plugins screen (Plugins > Add New), the button currently remains as a disabled "Updated!" state. Users must navigate to the Installed Plugins screen to activate it.

This PR brings consistency with the plugin installation flow: after successfully updating an inactive plugin, the button changes to "Activate" (or "Network Activate").

The Changes

1. wp_ajax_update_plugin() (src/wp-admin/includes/ajax-actions.php):

   • Added activateUrl generation when the updated plugin is inactive and the current user has the activate_plugin capability (matching the logic in wp_ajax_install_plugin()).

2. wp.updates.updatePluginSuccess (src/js/_enqueues/wp/updates.js):

   • Added a call to wp.updates.checkPluginDependencies() when response.activateUrl is present in the response.

3. wp.updates.checkPluginDependenciesSuccess & wp.updates.checkPluginDependenciesError (src/js/_enqueues/wp/updates.js):

   • Extended selector matching and class removal to include .update-now alongside .install-now so update buttons seamlessly transform into .activate-now buttons.

How to Test

1. Ensure an inactive plugin with an available update is installed on the site.
2. Navigate to Plugins > Add New.
3. Search for the inactive plugin.
4. Click Update Now.
5. After the update completes, observe the button transition from "Updating..." → "Updated!" → "Activate".
6. Click Activate to verify one-click activation works directly from the card.

Fixes #65909.

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