Install a tool to clean up unused exports over time

[rikukissa]

Description

Tech tasks

• Install https://github.com/webpro-nl/knip
• Inspect how many issues we have in the codebase. If the issues can be fixed in a few hours, fix the issues.
• Configure knip so that the Github CI creates an error in the linting pipeline if the number of unused exports increases in a PR. If you did however clean up all unused exports, then configure the pipeline to not allow any unused import unless explicitly defined as allowed

https://knip.dev/guides/using-knip-in-ci
https://knip.dev/reference/cli#--max-issues

[jamil314]

PR