Filter to allow modification of wp_editor settings for product short description

To make things simpler for my client (and to reduce the risk of them making a mess of the carefully crafter product archive pages on the front end of their site) I wanted to remove the "Add Media" button from above the TinyMCE editor in the Product Short Description meta box.

I was debating whether to just make a pull request to simply remove the media buttons y default, but though some people might actually have good reasons to place images and stuff within their short descriptions. So I decided to make this filterable. See example use case below:

```php
add_filter( 'woocommerce_product_short_description_editor_settings', 'remove_short_desc_media_buttons' );
function remove_short_desc_media_buttons( $settings ) {
    $settings[ 'media_buttons' ] = false;
    return $settings;
}
```

Don't know if you agree with the name I've given to the filter? Maybe it's a bit long, but at least it's descriptive! Feel free to change it if you prefer something shorter.