Jump to the center of the bounding box if find-data doesn't find data

[philippotto]

URL of deployed dev instance (used for testing):

• https://jumptolayercenter.webknossos.xyz

Steps to test:

• open a dataset for which find-my-data fails and open use the find-my-data feature. it should jump to the middle of the layer's bbox.

Issues:

• fixes Show and jump to center of layer bounding boxes  #4287
• fixes Make navbar red when saga crashes #4322 (tested by throwing an error in the save saga and ensuring that the navbar turns red)

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• Updated changelog
• Ready for review

[philippotto]

(I also covered #4322, since it's only a two line change.)

[daniel-wer]

Awesome 🎉