Image Resizer: Fill shouldn't crop faces

### Description of the new feature / enhancement

The current behavior of the **Fill** mode in Image Resizer is to crop the image to the specified ratio anchored to the center of the image. This usually works great unless the subject(s) of the photo are skewed away from center.

It would be super convenient if this mode detected the faces in the image and made a best effort to not crop over a face. If it can't be avoided, it should continue to anchor to center of the photo.

### Scenario when this would be used?

I use Image Resizer to scale and crop photos to fit a digital picture frame. I've noticed a few where the people have been cut off. This would greatly streamline my workflow.

### Supporting information

Current behavior | Proposed behavior
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The issue names no files, tests, or entry points. Start by locating Image Resizer's Fill-mode crop implementation and any existing image-processing tests; define how face-aware positioning should work and verify that center anchoring remains the fallback when faces cannot be avoided.

Written by the indexing model from the issue text.