Simple Payments name on Export page

#### Steps to reproduce the issue

1. Go to /wp-admin/export.php on a WordPress.com Premium or Business site
2. In the list there is a post type called `Product`

#### What I expected

Didn't expect to see this here at all as I don't have a store installed, or when I do have a WooCommerce store the products are in `Products` not `Product` (singular).

#### What happened instead

The presence of this item is fairly confusing. With a bit of investigation I found that it was the `jp_pay_product` post type, which is Simple Payment buttons. I like that these can be exported, but I think the post type name shouldn't be "Product". It could be "Simple Products" to be consistent with the plural format of all the other exports, and also to relate it to the Simple Payments Button and not confuse it with WooCommerce Products.

Start by searching for the `jp_pay_product` post type and inspect how its label appears in `/wp-admin/export.php`. Done means the export list identifies Simple Payments products without confusing them with WooCommerce Products, while preserving export support; verify on the WordPress.com Premium or Business setup described.

Written by the indexing model from the issue text.