[BUGFIX] Load icons for localization wizard properly

Due to the current API implementation multiple icons can't be loaded
in a single $.when() call. This causes issues after the icons are cached
as the return value of the promise changes.

The icons are fetched one by one in nested calls to workaround the issue.

Change-Id: Ifdd6622e5f4cd020dcb3a5ae76eaf0321942b936
Resolves: #72489
Releases: master, 7.6
Reviewed-on: https://review.typo3.org/45536


Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Stefan Froemken <froemken@gmail.com>
Tested-by: Gianluigi Martino <gmartino27@gmail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>