Set tag to empty string on ACNH item endpoints

[KevinPayravi]

On the wiki, we may soon remove the tag field from ACNH items, as this is purely used for sorting in-game, and is not a reliable indicator of anything useful. The function array is what actually holds useful functionality data.

Before the removal takes place on-wiki, we will need to:

• update the ACNH item endpoints to remove tag from the query.
• re-insert a tag field in the response body, with an empty string as the value (to ensure nothing breaks for existing users). This can be versioned.