Perform dead code analysis with Knip (#2575)

* Install Knip

* Clarify an import that was confusing Knip

* Fix issues detected by Knip

Including cleaning up some unused code and dependencies, using a React hook that we unintentionally stopped using, and also adding some previously undeclared dependencies.

* Run dead code analysis in lint script and CI

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Co-authored-by: Timo <toger5@hotmail.de>

.github/workflows/test.yaml

@@ -21,7 +21,8 @@ jobs:
         run: "yarn run test:coverage"
       - name: Upload to codecov
         uses: codecov/codecov-action@e28ff129e5465c2c0dcc6f003fc735cb6ae0c673 # v4
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
         with:
           flags: unittests
-          token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: true