Only create queue items for files that could contain EXIF data

Problem/Motivation

Currently, the form for retro-actively cleaning a directory will create a queue item for all files in the directory. We can probably already to a first screening based on file extension.

Steps to reproduce

1. Submit the form at /admin/config/media/exif_manipulate
2. Inspect the queue table
3. See that there are entries for files that are not images

Proposed resolution

Check the file name and only add files to the queue that end in an extension that might contain EXIF data. Maybe this should be configurable, e.g. with a checkbox on the form, in case there is some setup that does not rely on filename extensions.

Remaining tasks

• Implement change
• Create merge request
• Review
• Merge

User interface changes

None.

API changes

None.

Data model changes

None.