chore: migrate to ESLint v9

[susnux]

☑️ Resolves

It is a huge PR 🙈
But this is also a huge project!

So this basically migrates from old ESLint v8 to the currently support ESLint v9.
This means we now use the new flat configs and have to use the new nextcloud eslint config.
For review I recommend to either just scroll through the changes to see if there is something weird,
or to do it on a per commit base, as I tried to split every manual change.

• First commit is just the update of the config + dependencies (infrastructure changes).
• Second commit is the largest and basically npm run lint:fix - which contains some unwanted or not that nice changes
• For those are the next commits:
  • Fixing license comments that are not separated from imports and thus used as the import doc block
  • Fixing empty doc blocks for functions
  • Sub-optimal indention - yes its valid but there are better ways with less git diff in the PR so applied them
• And then there are some commits fixing things ESLint cannot autofix. Please refer to the commit messages why they are needed.

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 2️⃣ Backport to stable8 for maintained Vue 2 version or not applicable

[ShGKme]

Are these changes necessary?

• It is a new translation string - requires updating all translations
• Does Transifex check that every translation also uses non-breaking space?

[susnux]

Does Transifex check that every translation also uses non-breaking space?

Not sure if enforced on their side, but I know that this was discussed with the translators to always use nonbreaking space there if possible.

It is a new translation string - requires updating all translations

Yes but in the meantime - as you can see - its already fixed here so its stays translated.

[ShGKme]

Yes but in the meantime - as you can see - its already fixed here so its stays translated.

Does it update values in Transifex, if we change translations in the source?

[susnux]

You mean in the translations? No.
But it helps with keeping translations until the translators had time to adjust them - as otherwise all of those would be lost until they are re-translated just because of whitespace change

[susnux]

Fixed the commits:

• f8fbc1d (remove default and adjust the then failing test case)
• 5efb9ed (correct indention of the colors to make the translators comments work)

[susnux]

• Rebased and resolved conflicts
• Use new eslint-config release where the only change is that we could drop some parts of our custom config here