Make the settings page capability filterable

Instead of using hard coded manage_options capability to add UserWay menu item, you should make it filterable, so that we can give access to a any capability we prefer.

// Current method in includes/admin.php
add_menu_page( 'UserWay', 'UserWay', 'manage_options', 'userway', 'usw_userway_settings_page', 'dashicons-universal-access-alt' );

// New method
add_menu_page(
  'UserWay',
  'UserWay',
  apply_filters( 'usw_settings_capability', 'manage_options' ),
  'userway',
  'usw_userway_settings_page',
  'dashicons-universal-access-alt'
);