Upgrade eslint (#1014)

It's apparently forced now to use the eslint.config.js instead of
.eslintrc

It got more strict with requiring the underscore on unused vars like
`catch(_err)` , but that was all

Closes #1012
Closes #995
Closes #992

## Launch Checklist

<!-- Thanks for the PR! Feel free to add or remove items from the
checklist. -->


 - [ ] Briefly describe the changes in this PR.
 - [ ] Link to related issues.
- [ ] Include before/after visuals or gifs if this PR includes visual
changes.
 - [ ] Write tests for all new functionality.
 - [ ] Add an entry to `CHANGELOG.md` under the `## main` section.

cypress/e2e/modal-driver.ts

@@ -8,8 +8,8 @@ export default class ModalDriver {
     fillLayers: (opts: { type: string; layer?: string; id?: string }) => {
       // Having logic in test code is an anti pattern.
       // This should be splitted to multiple single responsibility functions
-      let type = opts.type;
-      let layer = opts.layer;
+      const type = opts.type;
+      const layer = opts.layer;
       let id;
       if (opts.id) {
         id = opts.id;