Plugins: Ensure wp_get_plugin_action_button() returns a string.

[57545] introduced `wp_get_plugin_action_button()`. This function is documented to return a `string`. However, if the user does not have the appropriate capabilities, it returned `void`, which is unexpected.

Resolves the issue by moving the `return $button` to the bottom of the function to ensure it always returns a `string` type. On success, the button's HTML string is returned; else, an empty string is returned.

Unit tests are included.

Follow-up to [57545].

Props costdev, rajinsharwar, hellofromTonya.
Fixes #61400.
Built from https://develop.svn.wordpress.org/trunk@58396


git-svn-id: http://core.svn.wordpress.org/trunk@57845 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/plugin-install.php

@@ -912,7 +912,7 @@ function install_plugin_information() {
  * }
  * @param bool         $compatible_php   The result of a PHP compatibility check.
  * @param bool         $compatible_wp    The result of a WP compatibility check.
- * @return string The markup for the dependency row button.
+ * @return string The markup for the dependency row button. An empty string if the user does not have capabilities.
  */
 function wp_get_plugin_action_button( $name, $data, $compatible_php, $compatible_wp ) {
 	$button           = '';
@@ -1048,7 +1048,7 @@ function wp_get_plugin_action_button( $name, $data, $compatible_php, $compatible
 				}
 				break;
 		}
-
-		return $button;
 	}
+
+	return $button;
 }

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.6-beta2-58395';
+$wp_version = '6.6-beta2-58396';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.