Updated how $argsKey is generated to work with sub arrays

[Enchiridion]

I was trying to use a meta_query to pull data for a select field however the original code to generate a unique cache key was failing when it came across a sub-array. I changed it so it'll work with any data types now.

  array(
    'id'          => 'post',
    'title'       => '',
    'type'        => 'select',
    'width'       => '100%',
    'data'        => 'post',
    'args'        => array(
      'post_type'      => 'travel_tip',
      'posts_per_page' => -1,
      'meta_query'     => array(
        array(
          'key'     => 'sponsored',
          'compare' => '=',
          'type'    => 'NUMERIC',
          'value'   => 1,
        ),
      ),
    ),
  ),
),```

[kprovance]

Added manually w/credit given. Thanks! :)