[Products] Improve the logic of handling tags to avoid re-creating the existing ones

[hichamboushaba]

Currently, when the user selects some tags and saves them, the app will always call POST /wc/v3/products/tags/batch to create them, even when the selected tags already exist, we need to update the logic only to create the new ones, which should make the experience snappier when the user selects only existing tags from the autocomplete field.

[dangermattic]

Thanks for reporting! 👍