Output filename with exotic characters is corrupted

[isaomatsunami]

East Asian Characters in Project name are corrupted in exported files.

To Reproduce

1. First, import the attached xls file, which has a filename of German-Japanese-French-Chinese characters.(and contains such characters inside cells too). Project names are not corrupted.
   äöüßいろはにàçéùè§繁體字.xls.zip
2. Then, Export data as tsv/csv/excel
3. Finally, the output filename is "äöüß????àçéùè§???-xls.csv". German/French are preserved but Japanese /Chinese are not.

Versions

• Operating System: Mac OS
• Browser Version: Firefox 61, Safari
• JRE or JDK Version: java version "11.0.1" 2018-10-16 LTS/Java(TM) SE Runtime Environment 18.9 (build 11.0.1+13-LTS)/Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.1+13-LTS, mixed mode
• OpenRefine: 3.5-SNAPSHOT

Additional context

The problem of the same kind on importing files with exotic characters is perfectly resolved. Huge thanks to dev team!

[gitonthescene]

Possibly related to #3277?

[gitonthescene]

Actually, it looks like the filename is set here and passed to the browser in the Content-Disposition header.

This doc seems to suggest the unicode needs to be url encoded with a byte-encoding specified. I think OpenRefine already packages PercentEscaper from guava.

In short, this looks fixable.