Test 'oxlint' in the Authoring MFE

I'd like us to consider replacing eslint with oxlint across all Open edX frontend repos. This ticket is to track work to test Oxlint in this MFE's codebase. See the related PRs for findings.

PR to test oxlint in this repo on a trial basis: https://github.com/openedx/frontend-app-authoring/pull/2847

Issues found from testing

• 104 missing/spurious await statements in test code https://github.com/openedx/frontend-app-authoring/pull/2560
• 50+ additional missing/spurious await statements https://github.com/openedx/frontend-app-authoring/pull/2592
• 8 redundant declarations of undefined type on optional parameters https://github.com/openedx/frontend-app-authoring/pull/2589
• 110 unused error variables https://github.com/openedx/frontend-app-authoring/pull/2591
• 15 questionable .toString() usages https://github.com/openedx/frontend-app-authoring/pull/2597
• 2 very bad usages of eval() ! https://github.com/openedx/frontend-app-authoring/pull/2848
• 2 nullish coalescing operators used pointlessly https://github.com/openedx/frontend-app-authoring/pull/2849
• 52 type issues of various severity https://github.com/openedx/frontend-app-authoring/pull/2850

Private ref MNG-4763