"Files exists" API check only checks for MID, but should also check for QID

[hay]

When checking if a file has already been depicted the tool currently only checks for the MID. However, a media file might depict multiple items, e.g.

https://commons.wikimedia.org/wiki/File:England_Olympic_polo_team_1920.jpg

Depicts multiple people, many of them might have a Wikidata item. Hence, the files exists API should check for the combination of MID / QID to prevent this problem.