refactor: improve data layer for Search feature

Description

Please review commit by commit.

Only the first two of the commits need to be reviewed as new commits. The remaining ones were already reviewed in previous MRs. Still, feel free to give it another look.

Screenshots

Technical details

Tests

Issues

https://gitlab.e.foundation/e/os/backlog/-/issues/3503

10 commandments of code review

👪 ❤️ https://gitlab.e.foundation/groups/e/-/wikis/contribute/development-processes/code-review-guidelines