Update Eslint to from v9 to v10

[SjurSutterudSagen]

There has been a new version of Eslint released since the beginning of the year, but some of the plugins we use have not been updated to support it. This has meant we have not been able to update to the new version, even though it is maybe 5+ months since it was released.

We need to sit down and go through the plugins and really consider if we should change to something else.

Dependabot PR for the update: #1340

I think there is atleast one more plugin holding us back than the one mentioned in that pull request, so we need to look for alternatives to that one too.

Eslint v9 EOL is 2026-08-06
https://eslint.org/version-support/

[SjurSutterudSagen]

Atleast some of the plugins missing Eslint 10 support:
https://github.com/jsx-eslint/eslint-plugin-react
https://github.com/jsx-eslint/eslint-plugin-jsx-a11y
https://github.com/import-js/eslint-plugin-import

Not maintained? 10 months since any commit:
https://github.com/prettier/eslint-config-prettier

Possible alternatives:
https://www.npmjs.com/package/eslint-plugin-import-x

(not necessarily complete list)