[BUGFIX] Trigger `change` event after calculating slug

When the slug is calculated by using the according button, the `event` is
now triggered to let the user know that the field value has changes and
to invoke the "You have unsaved changes" modal when closing the form.

Resolves: #86190
Related: #86077
Releases: master
Change-Id: I6eb4e11252562f53e637e3a1abdd7b02a8f73a5a
Reviewed-on: https://review.typo3.org/58218


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: rolandgolla <rolandgolla@gmail.com>
Tested-by: rolandgolla <rolandgolla@gmail.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Richard Haeser <richard@maxserv.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>