Check dependencies after installing plugin via "Add New".

[costdev]

After installing a plugin via the "Add New" screen, the "Install Now" button changes to "Installed" then "Activate".

This PR checks whether the plugin has any inactive dependencies. If so, the "Install Now" button changes to "Installed" then "Cannot Activate".

For the feature plugin, a custom script is used which overwrites wp.updates.installPluginSuccess(). For a Core merge, the changes can be made directly in Core's src/wp-admin/js/updates.js, and the admin_enqueue_scripts hook can be removed in WP_Plugin_Dependencies::start().

Steps To Test

Open DevTools on the Network tab.

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Scenario 1: A plugin with no dependencies

1. From Plugins > Add New, install a plugin with no dependencies.

Expected results:

• The button should read "Activate".
• The admin-ajax.php response should indicate success.
• A data: { slug, message } entry should indicate that the plugin has no required plugins.

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Scenario 2: A plugin with no active dependencies

1. From Plugins > Add New, install a plugin with two dependencies (try searching sso metadata, for example).
2. From the plugin card, click "View details" on both dependencies and install them.
3. Wait about 10-30 seconds, then refresh the page. (I know. This is the next bit we need to handle.).
4. Now click "Install Now" on the dependent plugin.

Expected results:

• The button should read "Cannot Activate".
• The admin-ajax.php response should indicate failure.
• A data: { slug, errorCode, errorMessage, errorData } entry should mention that both dependencies must be activated first.

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Scenario 3: A plugin with one active dependency

1. Delete the dependent plugin, but keep the dependencies.
2. Navigate to Plugins > Installed plugins and activate one of the dependencies.
3. Navigate back to the "Add New" screen.
4. Click "Install Now" on the dependent plugin.

Expected results:

• The button should read "Cannot Activate".
• The admin-ajax.php response should indicate failure.
• A data: { slug, errorCode, errorMessage, errorData } entry should mention only the inactive dependency must be activated first.

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Scenario 4: A plugin with all its dependencies active

1. Delete the dependent plugin, but keep the dependencies.
2. Navigate to Plugins > Installed plugins and activate the remaining dependency.
3. Navigate back to the "Add New" screen.
4. Click "Install Now" on the dependent plugin.

Expected results:

• The button should read "Activate".
• The admin-ajax.php response should indicate success.
• A data: { slug, message } entry should indicate all required plugins are installed and activated.