[BUGFIX] Always show download icons in language pack module

The Install Tool module "Manage Language Packs" is improved by the
following changes:

* If all language packs of an extension are available, the download icon
is still shown to make downloads of a single language pack per extension
possible.
* The icon itself changed from refresh to download as there is no
refresh possible. There is no lock on a specific date or version to
reload language packs. Every download can contain new or changed
translations.

Resolves: #86535
Releases: master, 9.5
Change-Id: I130c169b933b6e4b13c533928a46984bcb93979e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64003


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Josef Glatz <josefglatz@gmail.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Josef Glatz <josefglatz@gmail.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>