Use Promise.allSettled for multiple async tasks

[AkalUstat]

For example, in this thread https://github.com/KhalisFoundation/banidb-api/pull/204#discussion_r457812309

Promise.allSettled (es2020) doesnt short circuit if one task fails.

Ex: fetching 20 angs. If one fails, it won't prevent the successful 19 from going through