Translate export columns of task results

[eduardomozart]

When clicking on the Export results of tasks button, the column titles of the exported file are in English.

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[eduardomozart]

Decided to close this PR since other informations are already shown in English since PR #601 (the column "Last message" will show the message in EN now), so it make sense to keep the column names in English, too. If handling translation of last_log entry on CSV file, the PHP function normalizer_normalize($exec['last_log'], Normalizer::FORM_C) should be implemented since characters with accents (é) aren't being rendered as expected on Excel because most TTF fonts are Unicode instead of UTF-8, e.g. in UTF-8, the character "é" can be represented by "e + '", while Unicode represents it as an entity "é". As most fonts doesn't support UTF-8, they will print "e" followed by an square, as can be seen on the print below: