Bug #78457 Use gettext and .po(t) files for translations

Description:
Please use gettext for translating strings in the server and client if possible.

This would:
- Not only translate errors (not all translated errors are really errors now...)
- Allow the different translation communities to start translating MySQL.
- Allow the use of tools like transifex, launchpad, poedit
- Automatically mark translated strings as fuzzy when the original changes.

https://www.transifex.com/
https://translations.launchpad.net/
https://poedit.net/

How to repeat:
See description

Semi-relatedly, if server error log messages are to be translated at some point in future, I wish InnoDB team did not migrate from printf("foo bar %s baz %d") diagnostics to log << "foo bar " << str << "baz " << num, but used e.g. Boost::Format: log << format("foo bar %1% baz %2%") % str % num

Posted by developer:
 
Reported version value updated to reflect release name change from 5.8 to 8.0