プラグイン管理画面の設定リンクを追加する

<?php

class test_plugin {
  const PLUGIN_SLUG = 'test_plugin';

  function __construct() {
    add_filter( 'plugin_action_links_' . plugin_basename(__FILE__), array( $this, 'add_action_links' ) );
  }

  function add_action_links( $links ) {
    $new_links = array();

    $setting_url = admin_url( 'admin.php?page=' . self::PLUGIN_SLUG );
    $add_links['setting'] = '<a href="' . esc_url( $setting_url ) . '">' . __( 'Settings' ) . '</a>';

    $new_links = array_merge( $add_links, $links );

    return $new_links;
  }
}