Write translations of strings, extracted from info.xml (name, summary and description) back to info.xml

(logical continuation of https://github.com/nextcloud/docker-ci/issues/93)

It is exactly, as former dev is stating there: https://github.com/nextcloud/appstore/issues/691#issuecomment-624560952

Result should be as can be seen for example in info.xml file from this file:

https://github.com/julien-nc/cospend-nc/releases/download/v1.5.8/cospend-1.5.8.tar.gz

(no link to git repo, because in this case is file created during release trough script https://github.com/julien-nc/cospend-nc/blob/main/l10n/descriptions/gen_info.xml.sh - probably due different translation platform used)

Idea is to mark somehow (some identifier into notes to string perhaps? As is done for .vue files) these strings, found in info.xml, during scrapping from source code for source strings to Transifex and then write their translation during sync from Transifex to app repo not (only) into .js .json files in l10n dir, but instead to (or at least also) into appinfo/info.xml (as in mentioned example).

This way translations of name, summary and description will be used at all in app store and apps.nextcloud.com (as is in mentioned example with app Money Buster). Translations are log time already done, so effect on user experience would be intermediate...

Thanks :-)

Start with the linked docker-ci issue #93 and the referenced appstore comment to understand the intended synchronization flow. Compare the example info.xml in the Money Buster release with the app metadata and inspect cospend-nc's l10n/descriptions/gen_info.xml.sh. Done means translated name, summary, and description values are written into appinfo/info.xml during synchronization.