[Mediawiki-i18n] Bug fixes in Translate's sync, statistics, management

[Federico Leva (Nemo)]

Thanks to Glaisher (and Kunalgrover05),* this month multiple 
long-standing bugs in Translate were fixed, with considerable 
improvement of the translation workflow. Hopefully we'll have less 
headaches for everyone!

You can see a list at 
https://phabricator.wikimedia.org/maniphest/query/cmMEagL0pJdl/#R for 
instance, if you don't attentively follow Tech News and translation 
noticeboards.

Highlights for translators:
* Translation page does not contain the latest translations/last 
translation https://phabricator.wikimedia.org/T48716#2203121 / 
https://phabricator.wikimedia.org/T53731#2194277 (backlog still in the 
works)
* Edit summary: https://phabricator.wikimedia.org/T48924

Highlights for translation admins, administrators, patrollers:
* Deletion: https://phabricator.wikimedia.org/T41415#2269696
* Statistics: https://phabricator.wikimedia.org/T49864#2273458 / 
https://phabricator.wikimedia.org/T104172 / 
https://phabricator.wikimedia.org/T106262#2206626
* Parentheses: https://phabricator.wikimedia.org/T53226#2279459

Nemo

(*) And an extraordinarily fast code review by Nikerabbit, reflected in 
https://www.mediawiki.org/wiki/Wikimedia_Language_engineering/Code_review_statement_of_intent 
.