Make React frontend capable of reading API results under a results key

[RobertJoonas]

Changes

With the new imported data filtering feature, we'll start returning warnings in the dashboard API results, which means we'll need to move the actual list of results under a separate results key.

This PR is a preparation in order to not break the frontend when suddenly receiving API results under a results key. For some time, we'll need to be able to handle both a straight-up list response, or a map, containing the results key.

Tests

• [x] This PR does not require tests

Changelog

• [x] This PR does not make a user-facing change

Documentation

• [x] This change does not need a documentation update

Dark mode

• [x] This PR does not change the UI

[RobertJoonas]

Is there a plan to clean up the fallbacks once backend changes are done as well? I'm asking because IMO it doesn't make sense to keep accepting multiple different response formats when we know for sure what is being returned from internal APIs.

Yes, @ukutaht. The PR that implements filtering will remove it so we'll start relying only on the results key.