Make tag search precise

[philippotto]

The current tag search produces false positives if the tag name also appears somewhere else in the annotation properties.

URL of deployed dev instance (used for testing):

• https://___.webknossos.xyz

Steps to test:

• assign a t tag to an annotation in the dashboard
• rename another annotation to contain a "t"
• click on the t tag and check that only the one annotation is shown

Issues:

• fixes Tag selection of annotations does not work with single letter tags #7629

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(Please delete unneeded items, merge only when none are left open)

• Updated changelog

[MichaelBuessemeyer]

Thanks for fixing this 🙏 🚀.

The code looks good to me ✔️

Edit: Testing also worked 🎉