[BUGFIX] Access Close.html from Resources/Public/Html/

Clicking the close button in a editing popup accesses Close.html in
Resources/Public/Html/ which is a folder accessible by a web user
instead of Resources/Private/Templates/ which lead to a HTTP 403 error
on closing the popup.

Releases: master, 8.7, 7.6
Resolves: #83258
Related: #68108
Change-Id: Ibe7e328936240df436a3c9585e53122f1577dc6e
Reviewed-on: https://review.typo3.org/54983


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>