Check translations for bogus characters
This ticket is a cousin of legacy/trac#30054 (moved). We need some script that checks translations for bogus characters before they get merged to our translations repository. Not doing so risks that entire bundles are non-functional up to the point that not even updates to newer versions work anymore (see: legacy/trac#31886 (moved) for such a case, although the update still seemed to work I think). We should check for escaping issues like legacy/trac#31929 (moved) as well. Any maybe more.