[TASK] Optimize Iso database updater code

This change restructures some code
within the new updateIsoDatabase.php importer
to keep proper sorting in label files,
which was uncoordinated before.

That's why the countries.xlf (english),
is now updated.

Code for further ISO imports are
prepared to reduce code duplication.

Resolves: #99642
Releases: main
Change-Id: Ia5e7356e200916254372dfd66e8e3c77add323ec
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77499


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>