[FEATURE] Add Preview Button to Item Shops

[Everade]

Is your feature request related to a problem? Please describe. The patch to show the Equipment Preview button on the cash shop works just fine. However the Point Shops aka "old Cash Shop / Item Shop" doesn't support the Preview button.

Specifically speaking about the "itemshop" script function in rAthena.

Describe the solution you'd like Add the preview button support for equipment also to the old Cash Shop / Item Shop interface.

Additional context

[Neo-Mind]

This patch has been added. Just like for cash shop, it needs the server-side switch activated.