Refactor Playwright tests

[obulat]

Fixes

Extracted from #3605

Description

The test setup often includes closing banners and filters and turning on some feature flags. Several functions were used for that, and they were interfering with each other.

This PR uses cookies for this setup. The setCookies function is updated to correctly set and/or update the cookie values, stringifying and decoding them where necessary.
Now, instead of using the Close buttons in the UI, or the preference page to change the feature flag status, most of the tests set cookies before opening the first page.

This PR also moves around some of the breakpoints.describe and test.describe to prevent duplication.

In the attribution test, the function for collecting analytics events is used instead of an ad-hoc solution.

These changes are necessary to update Playwright from version 1.30 to version 1.40, and also for migrating to Nuxt 3.

Testing Instructions

CI should pass, and the changes should make sense.

Checklist

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[AetherUnbound]

Changes look great! Glad this can be put into a single function!

[sarayourfriend]

This PR uses cookies for this setup. The setCookies function is updated to correctly set and/or update the cookie values, stringifying and decoding them where necessary.
Now, instead of using the Close buttons in the UI, or the preference page to change the feature flag status, most of the tests set cookies before opening the first page.

Far out! That is a nicer approach for the individual test setup.

The only thing that strikes me is that the previous approach implicitly tested the process that sets the cookies. Now we don't do that, because we set the cookies directly. Should we also introduce new tests for the preferences and banner functionality... or are there already tests for that? If we need new ones, I think they should be in a follow-up issue, not in this PR.