Autosuggest product tags on bulk edit

This tiny change helps users quickly add tags to products using bulk
edit.

WordPress core provides this support for Posts when using Quick Edit and Bulk edit, but only for Quick Edit for custom post types.

Here's what it looks like with the change:
![](https://cloudup.com/cScytNqXcZj+)

props @bekarice for the suggestion :smiley: