Migrate to Turbo.js

[arkirchner]

Turbolinks.js has been archived for years now. Migration to the successor Turbo.js is straightforward.

Turbo.js also gives us some nice enhancement options.

[arkirchner]

Existing issues make the migration too time-consuming.

[MrSerth]

Even though the migration was time-consuming, we just finished it with #2998 and openHPI/codeharbor#2062.