I think it would be very useful to have Transliteration module support, to transliterate filenames during imports, and eventually a checkbox in the settings for enabling or disabling it.
Here is a patch for the functionality. I didn't provide the checkbox yet. It just simply transliterates if the Transliteration module is enabled and don't if it's not.
Migrate and Migrate Extras V1 are no longer supported. Moving request to V2.
Migration support for a contrib module should go into that module.
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